Category: Cold War US HMMWV Prototypes

United States of America (1981)
Light Utility Vehicle – 11+ Built

EMT XM966 Guided Missile weapons carrier variant. Source: XM966HMMWV.com
Starting from the late 1970s, the US Army was anxious to replace its mixed fleet of utility and light vehicles with a new general purpose multirole vehicle which had a high degree of mobility.
Starting in 1979, in anticipation of the requirement, Chrysler began work on its Expanded Mobility Truck (EMT). In February 1981, Tank Automotive Command (TACOM) finalized those requirements for the HMMWV and sent the final specifications out to 61 manufacturers inviting them to bid and submit designs. Chrysler was one of the companies which were to build a vehicle to meet the 1981 revised specifications.

Concept drawing submitted to TACOM. Source: Bill Munroe
The final requirements for the HMMWV (1981) were:

• Gross vehicle weight – 3268 kg
• Payload – 1135 kg
• Range – 483 kg
• Speed – 60+ mph (97+ km/h)
• Acceleration from 0-30 mph in 6-8 seconds
• Armor – protection from 16 g fragment at 225 m/s
• Engine – diesel
• Maximum dimensions – 4.95m long x 2.16m wide x 1.75m high (and be reducible)

Chrysler’s EMV (Expanded Mobility Vehicle) under trial in 1978. Source: Wheels and Tracks #4
Chrysler was one of five companies to submit designs and was one of just three selected in April 1982 to submit costs for the construction of 11 prototypes each for testing. Chrysler requested US$4.1 million to produce these vehicles. They delivered 11 prototypes to the Army for various testing, but, by 1982, the company was in severe financial trouble. In order to stay in business, Chrysler Corporation was forced to either sell off its defense arm or its car arm. They chose to sell the defense arm known as the Defense Products Division to General Dynamics Land Systems for US$348 million. This sold off all of Chrysler’s defense products, including their HMMWV prototype and the potential for a contract there, its Expanded Mobility Truck (EMT), and the profitable M1 Abrams tank. From 1982 onwards, work on this HMMWV prototype was no longer down to Chrysler but was a General Dynamics product.
Testing of the various prototypes was broken down into phases. ‘Phase I’ was ‘Durability and Operational Testing’ (DT/OT) and began in July 1982 focussing on how well the vehicles coped with a temperate climate (tests carried out at Aberdeen Proving Grounds, Maryland) and extreme heat (tests carried out in Yuma, Arizona).

Layout

The body of the XM966 was made from aircraft grade aluminum on a truck frame built for the prototypes by Sheller-Globe Truck Ltd. The early design featured a distinctive V-shaped front grille and flat bonnet and horizontally ribbed sides. After the take-over by General Dynamics Land Systems division (GDLS), this was modified to a small square front grille and round headlamps recessed into square holes in the front. The bonnet was also reduced in height at the sides producing a raised section in the center.

North American Deutz F8L model 610 air cooled diesel engine

Mobility

Mobility came from the 6.5-liter North American Deutz model F8L 610 diesel engine producing 160 hp at 3200 rpm. Unusually, this engine had no water cooling at all. It was an air-cooled engine selected for ease of maintenance and improved fuel economy over water-cooled models. It also happened to be made in Canada rather than in the USA, but General Dynamics claimed 50+% vendor support from US firms which avoided being rejected as a foreign applicant. Despite its advantages, the engine did not enter serial production upon the abandonment of the XM966 project.
The engine was connected to the heavy duty Chrysler A727 3-speed automatic transmission and NP218 (New Process – NP) 2-speed transfer case. Tires were either the 36-inch 36×12.5-16LT tire or 37 inch 37×12.5-18 nylon belted radials fitted with run flats devices capable of operating for up to 30 miles (48 km) at 30 miles per hour (48 km/h).

Armament

Armament variations considered for the XM966 were the GFE TOW anti-tank system, a universal mounting kit for machine-guns such as the M60 7.62 mm machine-gun, M2 .50 cal. heavy machine-gun, or Mk.19 40 mm automatic grenade launcher. The vehicle was also seen as offering the ability to use mortars for fire support and was also set up to transport the 60 mm, 81 mm, and 4.2” mortars.

‘Maxi’ Combat Ambulance variant of the XM966

Chrysler/General Dynamics’ EMT XM966. Illustration by Andrei ‘Octo10’ Kirushkin, funded by our Patreon campaign.

Proposed Platoon Coordination Center variant of the XM966.
Weapons Carrier variant of the XM966 with TOW ATGM mounted in Kevlar paneled turret

Variants

• Ambulance (Hard Top) – company level ambulance vehicle for evacuation of wounded
• Ambulance (Soft Top) – soft top variant specifically for US Marine Corps
• Utility – for general purpose duties, combat support with sub-variant roles:
  • Electronic Warfare Intelligence
  • Engineers
  • Fire Direction Center (FDC)
  • Fire Support Elements (FSE)
  • Forward Air Control (FAC)
  • General Purpose
  • Ground Surveillance Radar
  • Maintenance teams
  • Man-Portable Air Defence System (MANPADS)
  • Mortar transport
  • NBC reconnaissance
  • Tactical Operations Center (TOC)
• Weapons Carrier roof-mounted weapons stations:
  • TOW ATGM system
  • Universal weapons mount
• Platoon Coordination Center

The two types of ambulance, hard top and soft top, fulfilled different roles. The mini-version was fitted with a collapsible roof so it could fit inside of a helicopter. The small ‘mini’ ambulance would work at a platoon or company level and the ‘maxi’ ambulance at a company or battalion level. Both used a simple body fitted over the rear structure of the vehicle which could be dismounted with an expected space for 2 stretchers in the mini and 4 in the maxi.
The most common version which would have seen use if the Army had adopted the XM966 would have been the utility variant with simple plastic/rubber and canvas weather covers for the door tops and roof. The cab itself only seated 2 as it was really not much more than a commercial regular-cab pickup.
The weapons carrier variant is pictured as using the light protected body (although it is not clear if it was ever built) with the same kevlar shielded TOW unit on the roof. The TOW unit was adopted by the Army but without those shields.
Very little information is available on the other variants outside of photographs as the vehicle was a commercial and military failure, but they all have the same size cab and body varying only in the doors and what type of body is fitted to the rear. Had it been adopted the list of possible variations would have also increased.

The GD reworked EMT in 1982 showing the raised roof in place on this mini ambulance version. Source: Wheels and Tracks #4

A well-used looking EMT mini-ambulance variant pictured in a vehicle dump. Source: Bill Munroe

Surviving vehicles

Serial # 2 – private hands USA
Serial # 8 – Heartland Military Museum, Nebraska
Serial # 9 – Ft. Lewis Army Museum

Sources

xm966hmmwv.com
Warwheels.net
hmmwvinscale.com
brochures.slosh.com/hmmwv
Popular Science Magazine June 1982
hummerknowledgebase.com
HUMVEE, Bill Munro, 2003, Crowood Press
Wheels and Tracks #4
The Mid-1980’s Dodge HMMWV “Humvee” Proposal. Allpar.com

EMT XM966 specifications
Dimensions (LxWxH)	118.9” x 85” x 69” (3.02 x 2.16 x 1.75 m) Data plate for serial #8 shows 188.9” x 72.8” x 85”
Total weight, battle ready	4950 lbs (2,245 kg)
Crew	1+ (seats for 3 with an additional jump seat for a total of 4)
Propulsion	North American Deutz F8L 610 160hp air cooled diesel engine
Payload	3600 lbs (1,633 kg)
Speed (road)	Over 75 mph (121 km/h) (although speedometer only goes up to 60 mph)
Range	Over 300 miles (483 km)
For information about abbreviations check the Lexical Index

United States of America (1981)
Light Utility Vehicle – Unknown Number Built

Teledyne Continental was interested, like many other US firms, in the potential value of a large military contract for thousands of high mobility vehicles. When, in the late 1970s, the US Army wanted to replace its mixed fleet of utility and light vehicles with a new general purpose multirole vehicle, Teledyne took their chance.

Original Teledyne Continental Cheetah design with one-piece windscreen and headlamps sitting proud of the bonnet.

Teledyne Continental’s Cheetah HMMWV contender. Note how the sides are now flat and angled back slightly and that the headlamps sit under the line of the bonnet.
The Army released a letter of interest in July 1980 with final specifications being released in February 1981, when TACOM (Tank Automotive Command) once again changed the requirements for the HMMWV. They then sent the final specifications out to 61 manufacturers inviting them to bid and submit designs.

Teledyne Continental’s Cheetah HMMWV contender in cargo/personnel configuration.
Source: Wheels and Tracks #4
The final requirements for the HMMWV (1981) were:

• Gross vehicle weight – 3268kg
• Payload – 1135 kg
• Speed – 60+ mph (97+ km/h)
• Acceleration from 0-30 mph in 6-8 seconds
• Armour – protection from 16g fragment at 225 m/s
• Engine – diesel
• Maximum dimensions – 4.95m long x 2.16m wide x 1.75m high (and be reducible)

Of the 61 firms solicited, just five submitted designs and just three were selected, and Teledyne was one of them. Teledyne, therefore, submitted their bid for the construction of 11 prototypes for testing at a cost of US$4 million dollars which, per the contract, were supposed to be ready by May 1982, although some sources state that their bid was not even formally submitted until the 22nd November 1982.
Those 11 prototypes would be equipped and tested in the roles of TOW missile carrier, ambulance, armament carrier, and shelter carrier, although some latitude was given in terms of how to interpret these needs.

Submitted proposal for the Teledyne Continental Cheetah as a Weapons Carrier showing the arrangement of the TOW system on this Weapons Carrier version. Source: Bill Munroe
The design of the General Products Division of Teledyne Continental was called the ‘Cheetah’. It had been designed by Mobility Technology International (MTI), California, in the mid-1970s and bore a close resemblance to the XR-311.
The design was interesting enough that, even prior to trials, it attracted interest from the Italian firm of Lamborghini who saw the potential for their own lucrative contracts supplying a mobile off-road vehicle to the Italian Army and possibly for export too. Lamborghini’s interest led to them eventually building their own version, also called ‘Cheetah’, and showed to the world at the Geneva Motor Show in 1977.
MTI though was actually a subsidiary of Chrysler who was also bidding for the same XM966 CSVP contract. Chrysler, therefore, sold the rights to the MTI Cheetah to Teledyne Continental which officially parted Lamborghini from involvement.
Despite the vehicle now being the responsibility of Teledyne, there were still issues regarding the design and rumors of legal action from FMC over just how similar this vehicle was to their XR-311 design. This concern prompted some redesign work to avoid legal action.
All this had taken place in a short period of time from the mid-1970s to 1977/78 around the time of the CVSP. The CVSP program was over by 1979 though, and the HMMWV program was to take its place. If an order for up to 3,800 from the CVSP was tempting, then the potential for over 50,000 orders from the HMMWV program was irresistible and the pressure was on to win this deal.

Teledyne Continental Cheetah in ‘Maxi-Ambulance’ configuration in 1982. The inwards angling sides of the normal vehicle body are apparent here. Source: Wheels and Tracks #4

Soft-top version of the Teledyne Continental ‘Cheetah’ with the weather covers fitted. Illustrated by Andrei ‘Octo10’ Kirushkin, funded by our Patreon campaign.

Arrangement

The Cheetah was a conventionally arranged truck with the engine in the front and built on a tubular steel frame with an all-aluminum body. The engine was a 5.9 liter Chrysler V8 connected to a Chrysler A727 three-speed automatic transmission.

Teledyne Continental Cheetah in utility specification with weather covers fitted.
When the 1979 specification for the HMMWV came out it made specific requirements, one of which essentially excluded the Cheetah from being considered – the petrol engine. As a result, the engine choice was changed to a 140 hp Volvo six-cylinder diesel and then to a 6.9 liter International Harvester V8 diesel engine coupled to a General Motors model 475 three speed turbo-hydramatic transmission.

Looking more Mad Max than HMMWV this is the Teledyne Continental Cheetah HMMWV during trials in 1982 in Weapons Carrier configuration albeit with no weapons fitted. Source: Wheels and Tracks #4

Variants

As this vehicle’s development was a long drawn out failure, there is little accurate information to work out all of the variants of the Teledyne Cheetah and to describe them. Had they won the Army contract, the most common vehicle body used would have been the utility vehicle, fitted with simple canvas or plastic/rubber doors and roof to protect the crew of up to 4 from the elements.
The weapons carrier had some ballistic protection but this was not considered at any time to be bulletproof and was merely to protect against shell splinters. On this version, the windscreen, which was two part on all variants, had square type ballistic glass fitted as opposed to the rounded-corner type of laminated glass windscreen on the unprotected vehicles. The armored doors and windscreen also had folding flaps to protect the windows and featured rectangular slits so the crew could still see out, albeit with a little more protection, although how practical these actually are is highly questionable. A large hatch was fitted to the roof of this version on which a variety of weapons could be mounted, most obviously the TOW ATGM system with a series of kevlar shields around it to protect the gunner. This TOW mount was later adopted on other vehicles, albeit with the kevlar panels. In true ‘Mad-Max’ style, the back of the weapons carrier had two large clamshell doors with could open outwards providing a small amount of protection for a further load or armament.
For the ambulance variant, Teledyne opted for a standard type of rigid body vehicle, a maxi-ambulance instead of a mini-ambulance as other competitors considered. The maxi-ambulance was large enough to take 4 full-length stretchers, causing the body to substantially overhang the rear of the vehicle. As a consequence, the rear was angled sharply upwards to prevent it from grounding if the vehicle was off-road and a small series of steps folded down to allow access.

Termination

The Teledyne Continental ‘Cheetah’ was finally delivered to the Army and rigorously tested in 1982 along with submissions by other company. Despite whatever features the Army may have liked, the Cheetah lost out for the HMMWV contract to the AM General design. It received no orders and is not known to have been marketed elsewhere. At least one of the original prototypes survives at the US Veteran’s Memorial Museum in Tennessee.

Surviving Teledyne Continental Cheetah.

Specifications
Dimensions (L-w-H)	4.62 x 2.16 x 1.65 meters
Crew	1 – 4
Propulsion	5.9 liter Chrysler V8 petrol producing 180 bhp @ 4000 rpm 6 cylinders Volvo diesel producing 140 hp 6.9 liter International Harvester V8 diesel
Speed	90 mph (145 km/h)

Sources

HUMVEE, Bill Munroe
Wheels and Tracks #4
Ruoteclassiche.quattrouote.it
Lambocars.com
memorialmuseum.org

United States of America (1969-1985)
Development Program

The origins of the HMMWV go back to 1969 when FMC (formerly the Food Machinery and Chemical Corporation), based in California, started work on a high mobility scout car known as the XR-311.

XR-311 fitted for convoy/escort duty with .50 cal. heavy machine-gun fitted to a ring mount above the crew compartment. Source: Wheels and Tracks #4
A study by the US Army in 1972-1973 concluded that ⅔ (400,000 out of their 600,000) of their vehicles could be replaced with a single commercial light tactical vehicle without the need for good off-road performance which led to a consolidation effort in this utility class of vehicle. The outcome was the purchase of ¾ ton Dodge commercial pickup trucks which entered service as the M880 but this was still not an ideal solution to a long term problem.
By the late 1970s though, it was abundantly clear that the mish-mash of vehicles which had been in use as the Jeep was phased out of service was a hopeless situation. A new ‘Jeep’ was needed to fulfill a range of light-duty roles with good off-road mobility. The Army wanted to replace the M274 Mule, M561 Gama Goat, M792 ambulance, Dodge T125, Dodge M37, Dodge M880, Kaiser M715, and the M151 Jeep. Some preliminary work was conducted in 1974-1975 with the purpose to fill the ‘off-road’ gap in utility multi-role vehicles. At Fort Hood, the CJ-5 by Jeep, the Blazer from Chevrolet, the Ramcharger from Dodge, and the Bronco from Ford were all evaluated, but none of these vehicles were suitable.
Separately, the XR-311 was thoroughly tested by the US Military and trialed at the same time with numerous machine-guns and anti-tank weapons, such as the TOW and a 106 mm recoilless rifle. However, in a post-Vietnam defense budget era and lacking a specific requirement for such a vehicle no orders were made, although several were sold to Israel.
By 1977, Tank Automotive Command (TACOM), which in 1967 had replaced the older Ordnance Tank Command (OTAC), had seen the light and put forward the new XM966 Combat Support Vehicle Program (CSVP). The goal was to find a single vehicle to fulfill a range of combat roles, such as scouting, but most importantly, to carry the TOW ATGM, and it was estimated that about 3,800 vehicles would be needed.
Submitted bids for the XM966 CSVP were to come from AM General (who now owned all of the rights to the failed XR-311 from FMC), Chrysler, Teledyne Continental, and Cadillac Gage.
Teledyne Continental General Products Division submitted a design called the Cheetah which was actually designed by Mobility Technology International in California who were themselves a subsidiary of Chrysler. In order to produce the Cheetah though, Teledyne purchased the rights from Chrysler who were concentrating on their own submission named Saluki. Another competitor came in the form of a version of the ‘Commando’ armored car from the firm Cadillac Gage, whereas AM General initially simply submitted an improved variant of the XR-311.
By 1979, though the CVSP program was canceled by Congress which did not feel the value in spending a lot of time and money developing such a small number of vehicles and wanted a more capable platform for more roles. The requirements were changed and more rigid requirements were imposed with the release of the specifications the Army wanted to be filled. The requirements were now known as the ‘High Mobility Multipurpose Wheeled Vehicle’ of ‘HMMWV’ with an initial requirement for 50,000 vehicles.

Teledyne Continental’s HMMWV contender
The requirements for the replacement were:

• A single vehicle family of variants from the same platform capable of satisfying joint-force requirements.
• Excellent on and off-road performance.
• Total vehicle weight including payload not exceeding 7,500 lbs (3,402 kg).
• Payload of 2,500 lbs. (1,134 kg).
• Diesel engine with an automatic transmission capable of 0 – 30 mph in 6 to 8 seconds.
• Maximum road speed of at least 60 mph (97 km/h) and 40 mph (64 km/h) off-road.
• Range of autonomy of 300 miles.
• Light ballistic protection suitable to protect occupants against fragments up to 16 grams.
• Air transportable including helicopters and C-130 aircraft and ‘droppable’ by parachute system.

An armored variant of the XR-311 submitted for trials in 1977/78. Source: Wheels and Tracks #4
TACOM required 6 categories/roles to be able to be filled by this new HMMWV:

• Forward Observer vehicle
• Communications vehicle
• Utility truck
• Ambulance
• Weapons Carrier
• Personnel Transport

First pattern prototype of the AM General HMMWV.
They also set the maximum limits for the dimensions of the vehicle which would ensure it could be carried by air transport craft. Because it was estimated that the vehicle would spend 40% of its time off-road, it would have to be either full-time 4 wheel drive or selective. If it was a selective 2/4 wheel drive, then a further stipulation was that it must be able to change from 2 wheel drive to 4 wheel drive while on the move rather than stop to do so. This added complication simply led makers like AM General and Chrysler to have the vehicle in 4 wheel drive permanently and only the contender from Teledyne could be switched from 2 to 4 wheel drive on the move.

Second pattern prototype AM General HMMWV during testing configured as an ambulance. Source: slosh.com
As the vehicle selected would achieve very large orders for production, it is no surprise that so many firms would submit proposals to meet this requirement.
AM General submitted a revised vehicle after the 1979 HMMWV order. No longer would they be looking at the XR-311, but a newly designed vehicle based roughly on their own Jeep (SJ) vehicle. They built a prototype on a modified SJ Jeep frame and submitted it for testing at their own facility which was completed by February 1980. Five more vehicles were then built and sent to a private facility in Nevada for a 50,000 mile (80,500 km) mock trial of the tests the Army would put the design through.

Chrysler Saluki. Source: allpar.com

The low silhouette of the CSVP/HMMWV is apparent in the illustration along with the relatively short cargo space at the back. A single machine gun is mounted on top with no protection for the operator or driver. Illustration by Andrei ‘Octo10’ Kirushkin, funded by our Patreon campaign.

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On 8th July 1980, the project was formally approved by the Secretary of Defense and the entire HMMWV project was summed up that it “will perform the mission of all ¼ – 1 ¼ [ton] vehicles presently operating in the forward area”.
The Army released a letter of interest in July 1980 in anticipation of final specifications which came in February 1981 when TACOM once again changed the requirements for the HMMWV. They then sent the final specifications out to 61 manufacturers inviting them to bid and submit designs. Development officially began in July 1981.
The final requirements for the HMMWV (1981) were:

• Gross vehicle weight – 3268 kg
• Payload – 1135 kg
• Range – 483 kg
• Speed – 60+ mph (97+ km/h)
• Acceleration from 0-30 mph in 6-8 seconds
• Armor – protection from 16g fragment at 225 m/s
• Engine – diesel
• Maximum dimensions – 4.95m long x 2.16m wide x 1.75m high (and be be reducible)

Chrysler’s EMTV (Expanded Mobility Vehicle) under trial in 1978. Source: Wheels and Tracks #4

General Dynamics reworked version of Chryslers EMT shown with TOW ATGM and kevlar shields. Source: Wheels and Tracks #4
Five companies, American La France, FWD (Four Wheel Drive), Chrysler, AM-General (American Motors), and Teledyne Continental, submitted designs for this phase, and in April 1982 three were chosen to submit costs for the construction of 11 prototypes each for testing. These firms were Teledyne Continental ($4m), Chrysler Corporation ($4.1m), and AM General ($4m) – they were to have 11 vehicles ready before May 1982.
Those 11 prototypes would be equipped and tested in the roles of TOW missile carrier, ambulance, armament carrier, and shelter carrier although some latitude was given in terms of how to interpret these needs.
Testing of the various prototypes was broken down into phases. ‘Phase I’ was ‘Durability and Operational Testing (DT/OT)’ and began in July 1982 focussing on how well the vehicles coped with a temperate climate (tests carried out at Aberdeen Proving Grounds, Maryland) and extreme heat (tests carried out in Yuma, Arizona). Over 4,450 individual tests would be carried out to ensure each component met the stringent Army criteria including:

• 27 checks of operator control and accessories in the crew compartment.
• 146 checks on the engine.
• 40 checks on the brakes.
• 29 checks on the powertrain – from the engine to hubs.

The Durability tests were harsh – tests were to last 16 hours a day with drivers working shifts aiming to clock 20,000 miles per vehicle in the first 5 months alone.
Regarding weapons, all the prototypes examined as weapons carriers were trialed with M60 7.62 and M2 .50 cal. machine-guns and the Mk.19 40mm automatic grenade launchers. The AM General designs had brake problems during ‘Phase I’ and modifications were required before it could take part in ‘Phase II’ trials, but its parent company American Motors Corporation was in severe financial crisis and was forced to sell off AM General to LTV Aerospace and Defence for US$170 million in 1982. Another competitor, Chrysler was not faring well either and was forced to either sell off its defense arm or its car arm to stay viable. They selected to sell the defense arm known as the Defense Products Division to General Dynamics Land Systems for US$348 million in 1982, thereby selling off their entire military sector including not just the HMMWV prototype and the potential for a contract there but also its Expanded Mobility Truck (EMT) and M1 Abrams tank.
During ‘Phase II’ (automotive trials where the Army got to drive the vehicles), which started on November 1st 1982, and ‘Phase III’ (specific tactical terrain driving conditions such as rough terrain and deep wading), it was the AM General vehicle which was proven to be the most successful, but there were still problems. All told, thirty-three HMMWV prototypes were manufactured and subjected to 600,000 miles of testing on various terrain and in various environmental circumstances, not just at Aberdeen Proving Grounds (APG), but also with the US Marine Corps at Camp Pendleton and with the US Navy at the Navy Amphibious Base at Coronado, California. Tests of the HMMWVs though would later be heavily scrutinized as the Army had rushed its assessments. The original plan had been for production over 7 years, but the Army would subsequently make this just 5 years and the testing which was supposed to last 14 months was compressed into just 5. Indeed, the formal report on the testing problems had not even been finished before the production order was made which is an unusual state of affairs for a major military system.

One of the 11 prototype AM General HMMWVs seen in April 1982. Source: Wheels and Tracks #4
There were serious problems with reliability found during testing and some of these were immediately addressed, and additionally, although it was not a problem, the horizontal grille on the front was changed to a vertical grille, presumably to try and look more ‘jeep-like’. The Army had made its choice, the AM General design was to be the HMMWV they wanted, but that was not the end of the story.
It had taken years, but finally, the US Army had its ‘HMMWV’ design chosen and the contract awarded on 22nd March 1982 (GAO report states March 1983) was for the design from AM General for production over the next 5 years for over nearly 55,000 vehicles.
The official unveiling of the US Army’s new vehicle took place at the Farnborough Air Show in the UK in 1984 by US Defense Secretary Barry Goldwater.

First ‘Hummer’ rolls off the production line at Mishawaka, Indiana on the 2nd of January 1985. Source: unknown

A note on the name

The acronym HMMWV soon began to be simply called ‘Humvee’ before being shortened by AM General to just ‘Hummer’. AM General was owned by General Motors who also owned the ‘Jeep’ brand name, and having had a difficult experience in registering that brand name, they wasted no time in registering ‘Hummer’ and ‘Humvee’ as a brand name, with presumably an eye on the civilian sales marker.
In 1993, the first civilian ‘Hummers’ were sold by AM General, but soon after they sold all of their civilian marketing rights and brand name of ‘Hummer’ to General Motors who continued with it under the name ‘HUMMER’ – always in capital letters.
To further confuse the name issue there is also the ‘Heavy Hummer Variant’ or ‘HHV’ made by AM General and named by them when they still had the rights to the ‘Hummer’ name. Therefore, to be correct and to reduce confusion over the name, the military vehicle should always be referred to only as the ‘HMMWV’ or ‘Humvee’, the civilian vehicles made by AM General as ‘Hummer’ and those by GM as ‘HUMMER’.

Conclusion of development?

The AM General HMMWV had beaten the competition to win a significant contract from the military and production vehicles from the first contract were to incorporate the changes required after the conclusion of testing. It was not a cheap vehicle though, the base model HMMWV was US$20,410 and the weapons carrier versions US$28,382, meaning that the Army initially still used civilian trucks for general duties. Thus, despite having finally managed to get the all-purpose multi-role vehicle they wanted, they ended up using 70,000 civilian vehicles anyway, namely the Chevrolet Blazer to fill the M1008/M1009 Commercial Utility Cargo Vehicle (CUCV) requirement. The advantage at least was some interchangeability of engine parts between the two vehicles.
The HMMWV would go through progressive development as all vehicles do and be used for more than was originally intended. It remains an iconic military vehicle and has subsequently seen active service with numerous nations around the world although it is currently at the end of its practical user life with the US military. A whole family of vehicles based on the HMMWV has been created and the vehicle is likely to stay in service into the middle of the 21st Century.

Sources

HUMVEE, Bill Munro, 2003, Crowood Press
HMMWV Humvee 1980-2005, Steve Zaloga
TARADCOM Posture Report RCS DRCLD-101 – 1980
Hummer Humvee in Action, Jim Mesko
Wheels and Tracks No.4
GAO Report AD-A142 168 June 1984
RDI Task Final Report of Vehicle Performance Recorder, APG, May 1984
Hummer – The Next Generation, Michael Green

Tanks Encyclopedia Magazine, #1 Republished

The first issue of the Tank Encyclopedia Magazine has been remastered and rereleased. It covers vehicles ranging from the French WWI Frot-Turmel-Laffly Armoured Road Roller up to the Salvadoran Cold War Marenco M114 converted vehicles. The star of this issue is a full article on the Improved Protection version of the famous M1 Abrams – the M1IP.

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United States of America (1977-1982)
Light Utility Vehicle – Approximately 11 Built

When Tank Automotive Command (TACOM) announced in 1977 that they were looking for a multi-role vehicle with a high degree of mobility to perform a wide variety of general purpose duties, several firms were interested. The program from TACOM was for the XM966 Combat Support Vehicle Program (CSVP) and Chrysler was going to play a major role in competing for the contract which would be for thousands if not tens of thousands of vehicles.
Chrysler owned Mobility Technology International (MTI) in California, the same company who designed the Cheetah. However, they sold the design rights to Teledyne Continental in order to focus on their own project called the ‘Saluki’. At the time, Chrysler was having severe financial problems which may explain both why they chose to sell the advanced design from MTI to Teledyne and develop a more standard vehicle themselves.

The Chrysler Saluki during testing.

Layout

The Saluki was a relatively conventional vehicle as it was based on commercially available, well tested and proven truck components already on the commercial market. It would be built on a modified version of the standard Dodge ladder chassis. The engine would be the 195 bhp 5.9 litre petrol big block V8 coupled to a Chrysler A727 three speed automatic gearbox. Being commercially available the costs of tooling for construction were minimised by avoiding curves – hence the hard angular lines. The only version known to have been built was the ‘pickup’ style which is not surprising considering it was built from existing truck parts. Seating was for 2-3 at most. No armor or weapons were fitted.
The Saluki was tested at Chrysler’s own test ground in early 1981 but due to crippling financial problems, Chrysler sold their entire defence division to General Dynamics in 1982 including the Saluki, at which point it disappears. It’s unclear how many prototypes were actually manufactured or how much military testing was completed. Of the various weapons carrier types desired by the Army none are known to have been tested on the Saluki.
The Saluki was not a bad concept or its time. Commercially available components pre-tested made financial sense which would result in less research and development cost compared to the development and testing of brand new parts. Even so, this ‘discount’ design was still at US$4.1 million dollars for 11 prototypes by Chrysler in 1982, which meant the Army actually paid more for these 11 vehicles with off-the-shelf parts than they did for the Teledyne Continental (US$4m) or AM General (US$4) designs.
It was a better vehicle than the ones found it the US Army’s existing fleet. However it did not meet the criteria set out and tested by the HMMWV program. The engine was petrol rather than diesel and it did not have the required 16 inches of ground clearance. Regardless of what qualities it may have had as a design these two factors would have stopped it from going further. At least two are known to still exist – both in private hands in the USA.

Illustration of the Chrysler Saluki High Mobility Multipurpose Wheeled Vehicle (HMMWV) prototype, produced by Andrei ‘Octo10’ Kirushkin, funded by our Patreon Campaign.

Three view of the Saluki. Source: allpar.com

Surviving Saluki in private hands – the lack of ground clearance at the front is obvious. Source: allpar.com

Specifications
Dimensions (L-w-H)	4.47 x 2.16 x 1.96 meters (with roof, 1.52m without)
Propulsion	Chrysler 5.9 litre V8 petrol producing 195 bhp @ 4,400 rpm
Total Built	Aprx 11

Sources

HUMVEE, Bill Munro, 2003, Crowood Press
The Mid-1980’s Dodge HMMWV “Humvee” Proposal. Allpar.com

United States of America (1979-1983)
Light Utility Vehicle – 12+ Built

As well as the rebirthed XR-311, AM General submitted another design to try and win the lucrative XM966 contract for the High Mobility Multi-Purpose Vehicle TACOM (Tank Automotive Command) had demanded in 1977.
While the XR-311 was an ‘outside’ design they received via Food Machinery and Chemical Corporation (FMC) in 1975, the new High Mobility Multipurpose Wheeled Vehicle (HMMWV) XM966 would be a different vehicle to meet the same requirement. Work on this new vehicle began in 1979 with the amended HMMWV requirement.

First pattern of prototype AM General HMMWV during testing. The fact that it evolved from the XR-311 is obvious.
AM General were already manufacturing the M151 Mutt under contract and owned the Jeep brand name so could be seen as the inheritors of its pedigree. AM General also produced a 5.25 ton chassis for a conventional truck which was in service as the M715 with a ‘double-drop’ down ladder frame. The vehicle produced from this frame had a wheelbase of 3.2 metres (M715) or 3.35 metres (AM715).

Prototype of the AM General HMMWV during testing.
AM General built an initial prototype configured as a weapons carrier based on the modified ladder chassis of the ‘Senior Jeep’ (SJ, a civilian model) and M715. The frame was not like the XR-311 at all, the tubes being replaced with rails like on the SJ. However, this version featured 8 supporting cross braces for additional strength and rigidity instead of the 6 of the SJ. The chassis was steel but the bodywork would be aluminium.

Prototype of the AM Geneair-cooledduring testing.
The engine originally selected was that of the reworked XR-311, an air cooled 6.6 litre Deutz diesel coupled to a three speed Chrysler transmission but this was changed to a 130 bhp 6.1 litre General Motors V8 diesel engine coupled to a General Motors THM400HD Hydramatic three speed automatic transmission which was already in use by the Army in their M1008 Commercial Utility Cargo Vehicle (CUCV). That GM DDA V8 130 bhp engine was later changed once more to a 6.2 litre General Motors V8 diesel producing 150 bhp instead.

Second pattern prototype AM General HMMWV during testing configured as an ambulance. The front is now nothing like the XR-311 and much more HMMWV like.

Testing

AM General did a significant amount of testing of their own vehicle and, by February 1980, their HMMWV had covered over 17,000 miles (27,400 km). They then made 5 more vehicles which were sent to the Nevada Auto Test Center (NATC) for a 50,000 mile (80,500 km) pre-test. This was to simulate the sort of tests the Army would put the design to. This was well planned considering a year later the Army submitted final specifications it would need to meet.
Problems found during the initial trials were:

• Brake malfunctions
• Excess brake wear
• Power steering problems
• Fuel system leaked

AM General XM866 prototype fitted with TOW launcher behind Kevlar shields. Source: Bill Munroe

The Formal Process

The CVSP had initiated the process and the HMMWV program had continued it and in February 1981 the Army finalised what they wanted from this new vehicle inviting designs from 61 manufacturers. AM General were ideally placed to submit their own design therefore and submitted their proposal for US$4 million for the 11 prototypes required by the Army which would have to be delivered prior to May 1982.
AM General made 12 more prototypes which started testing under Phase 1 Durability and Operational Testing (DT/OT) in July 1982 in Yuma, Arizona (extreme heat) and Aberdeen Proving Grounds (APG), Maryland (temperate climate tests). During testing though, despite having had their vehicle evaluated in Nevada beforehand, there were serious problems with the brakes on this new vehicle and modifications had to be conducted in order to be permitted to take part in Phase II trials at Fort Hunter-Leggett in California which started on the 1st of November 1982. Phase II trials would also use soldiers as the crew which could be anticipated to mean somewhat more rigorous testing.
Phase III testing involved handling features including deep wading and it was after this that the AM General design had come out of top. Not problem free but rugged, durable, and mobile. In total about 600,000 miles of testing was carried out on the vehicles including trials at APG, Camp Pendleton (USMC), and in Coronado (USN).

Prototype AM General HMMWV during testing configured as a wrecker

Illustration of the AM General XM966 High Mobility Multipurpose Wheeled Vehicle (HMMWV) Prototype with a TOW launcher mounted behind Kevlar shields, produced by Andrei ‘Octo10’ Kirushkin, funded through our Patreon Campaign

Problems Found During Testing

• Headlamps (damaged by vibration) – relocation and additional cushioning from shock
• Weld fractures (particularly to the door area of the weapons carrier) – design change
• Hub castings (aluminium) – switched to cast iron
• Suspension arms (aluminium) – switched to steel
• Modifications of suspension springs and spring seats
• Modification of shock absorbers and mounts
• Leaks (powertrain) during fording – new sealing
• Redesigned air cleaner inlets
• Changes to engine accessory drive pulleys
• Altered exhaust system
• Lack of stability
  • shortened chassis frame
  • Modifications to the tyres
  • Engine mounting brackets
  • Redesigned front axle half shafts
  • Redesigned front prop shaft
  • Modified torque converter
  • Changed axle ratio
• Relocation of radiator
• Redesign of radiator fan
• Redesign of venting system

One of the 11 second pattern prototype AM General HMMWVs seen in April 1982. Source: Wheels and Tracks # 4
Although it wasn’t a problem, the horizontal grille on the front was changed to a vertical grille presumably to try and look more ‘Jeep-like’.
It had taken years but finally the US Army had its ‘HMMWV’ design chosen and the contract awarded on the 22nd March 1982 (GAO report states March 1983) was the design from AM General for production over the next 5 years for over nearly 55,000 vehicles.
There were serious reliability problems revealed during the testing which the Department of Defense glossed over. The AM General HMMWV had only managed 82 mean miles between unscheduled maintenance instead of the 320 miles required and only 367 mean miles between mission failure defects (those rendering the vehicle incapable of use without repair) as opposed to the 1,300 miles required. These faults created a 26% deficiency from performance to what was wanted.


The official unveiling of the US Army’s new vehicle took place at the Farnborough Air Show in the UK in 1984 by US Defense Secretary Barry Goldwater. The success was short-lived for AM General. They were taken over in September 1983 by the LTV Corporation and, despite the PR of the release of this vehicle, a 1984 report by the Government Accounting Office was scathing saying:
“… the Army’s decision to award a full-scale production contract was premature in view of reliability problems disclosed in the operational tests and that additional operational testing should have been performed before large sums of production dollars were committed… the HMMWV fell short by a wide margin of achieving reliability requirements due to many hardware malfunctions”.
The first production vehicle rolled off the production line on the 2nd January 1985. Over the next 4-5 years a total of 55,000 vehicles (see chart) were produced for the US military of which 39,000 were for the Army alone. Further numbers were also produced for foreign countries such that, after 10 years of production, over 100,000 HMMWVs had been built.

Variants

Weapons Carrier

This vehicle would have the ballistic protection required and a hatch in the roof with a weapons mount for a variety of weapons such as the 40mm automatic grenade launcher, a variety of machine guns, possibly a recoilless rifle, and the TOW ATGM system.

Utility

A majority of vehicles for the Army were to be in this configuration. Unarmoured and using only canvas, plastic, and rubber, doors and roof to keep the crew protected from the weather. This configuration would be the base vehicle for a variety of sub-variants for fulfilling minor roles or for carrying other box-bodies on the back.

Wrecker

Only a photograph is known of this variant which appears to be unarmoured and mounts a small winch and jib on the back. It would have been ideal as a light recovery vehicle for towing broken down HMMWVs etc. but not much else. Only one prototype is known.

Continuing Development

The HMMWV had been chosen and changes had been incorporated from the prototype to the first generation of production. The first HMMWV ‘Hummer’ rolled off the production line in Mishawaka, Indiana on the 2nd January 1985 and further contracts for production were to follow. The HMMWV was born and it would find use across the world in conflicts and peacetime with numerous nations.

Specifications
Dimensions (L-w-H)	4.7 meters long
Crew	1 +
Propulsion	6.6 litre Deutz V8 diesel, 6.1 litre General Motors DDA V8 diesel, 130 bhp @ 3600 rpm, 6.2 litre General Motors V8 diesel, 150 bhp @ 3600 rpm
Other specification as XR-311

Sources

Sources:
HUMVEE, Bill Munroe
Osprey Publishing, New Vanguard #122: HMMWV Humvee 1980-2005, Steve Zaloga
HMMWV – workhorse of the US Army, Carl Schulze
Hummer – The Next Generation, Michael Green

United States of America (1990)
Scout Vehicle – None Built

The High Mobility Multipurpose Wheeled Vehicle (HMMWV) or ‘Humvee’ hadn’t long been in the inventory of the US Military by 1990 and was already a significant improvement over the hodgepodge of commercial pickups and light vehicles employed to fill the gap left by the Jeeps.
The opportunity to use this new off-road platform as a dedicated scout vehicle was suggested by 1st Lieutenant Kenneth Deal in the November/December issue of Armor Magazine who pointed out that despite the capabilities of the HMMWV platform, none of the existing variants were suitable. It should be noted that Lt. Deal was at the time a serving officer acting as a Scout Platoon leader for 1-63 Armor.

HMMWV Scout concept by 1st Lt. K. Deal

The Deal Scout HMMWV

Lt. Deal suggested a new variant of the HMMWV halfway between the M966 hardtop and the M1038 ‘open top’. The M966 was seen as unsuitable primarily because armor was limited to just the Kevlar roof and the small hatch permitted just a single weapon mount. The M1038, on the other hand, could mount a variety of weapons, all of which could be used at the same time, but was unsuitable because of a complete lack of protection.
The new variant would have a hard rigid body, making use of Kevlar panels and a hardtop but with a very large rectangular hatch that permitted multiple weapons to be used. The suggestion was to take an existing M1038 vehicle and mount a new body onto it. The windscreens of the vehicle would have to be replaced with two Kevlar shutters, each with two rectangular vision slots and hinged at the top to fold back over the roof when not in use. If a windscreen was kept, Lt. Deal suggested some form of louver could be used instead to reduce the risk of glare from the glass giving away the position of the vehicle. There would be two side doors, one in each side, covered with Kevlar panels and each having a large rectangular window also to have some form of Kevlar shutter although it was not shown or described.
Underneath, the chassis would be fitted with skid plates to prevent damage to the powertrain and fuel tank when going off-road, a 5-ton winch on the front and a deep wading snorkel. Personal kit and other stowage would go on the outside of the vehicles with essential tools carried on the rear.
Inside, the crew area at the front would be unchanged but the rear would be arranged “much the same as the M113”. The large roof hatch could be closed when not in use and the entire area inside the compartment would measure about 3’ x 5’ (0.9m x 1.5m) providing space for ‘3’ crew consisting of the commander and two scouts. However, as the commander is provided with their own weapon station it seems Lt. Deal either meant a crew of 4, having omitted the driver or intended for one of the crew to act as driver permanently which would obviously mean only 2 of three weapon station could be used at one time. The additional space inside the vehicle was claimed to be suitable and large enough to accommodate specialist teams such as medics or sappers or even a Stinger team.

Front view of Deal’s Scout HMMWV concept

Armament

The author noted the general trend away from heavily armored and heavily armed reconnaissance towards light fast vehicle but nonetheless wanted plenty of firepower. An Mk.19 automatic grenade launcher or M2HB .50 cal. (12.7 mm) heavy machine gun, mounted on a swing mount as used on the M1 Abrams MBT, would provide 180 degrees of coverage across the front, fired by the Commander. Two M60 7.62mm machine guns would be mounted at the back, with one on each corner also with 180 degrees of arc thereby providing over 360 degrees of coverage between the three weapons. The crew would also have their personal rifles. All weapons were to be dismountable for ground use and all could be fitted with a small shield to protect the crew member when operating it.
Finally, smoke grenades would be mounted at the front and rear and a single Dragon anti-tank system should be carried to provide some additional heavy firepower. The author noted that “the use of TOW is actually overkill for the scouts; leave the killing to the tanks”.

Top view of Deal’s Scout HMMWV concept

Illustration of the High Mobility Multipurpose Wheeled Vehicle (HMMWV) Scout Concept, produced by Andrei ‘Octo10’ Kirushkin, funded by our Patreon Campaign

Electronics

The vehicle would be fitted with the 1780 AN/VRCI intercom so the crew could all talk without having to use speakers and maintain tactical silence. A land navigation system such as a GPS station along with a laser rangefinder would be used to prevent them from getting lost and providing accurate information on enemy positions. In order to report back, a quick erect AB903 antenna would be used.

Optics

Some HMMWVs already being used in the role of a scout vehicle for reconnaissance were already fitted with dismounted thermal imagers removed from the M60A3 and the author suggested that this TOW VAS11 system mounted in his concept would provide an excellent all-weather optic for the vehicle and would be mounted in the front right-hand side of the crew compartment.

Conclusion

The scout role is a very specialized one. Do you add armor which reduces mobility, do you expect your scouts to fight or just ‘see’? Different countries have different philosophies and a wide range of vehicle have been and still are used for the task. Reconnaissance work is far from simple and no answer is going to be perfect but in 1990, faced with a lack of other options, Lt. Deal (a serving reconnaissance officer) came up with a cheap, simple and effective modification to an existing vehicle which would seem to have fulfilled the role suitably. The ‘armor’ chosen would have barely been bulletproof but would have provided some protection. The firepower envisaged would have allowed plenty of fire to be thrown at the enemy if the vehicle was seen and the entire package was small enough that a single C-130 Hercules transport aircraft would be able to carry three of these vehicles along with the crew.

Post-Script

As it happened, none of these Scouts were built to Deal’s plan and, in hindsight, this might have been for the best.
In 1987, the RAND Corporation was commissioned to investigate scouting conceptual organizations for the US Military and found that 50% losses for scouts and commensurately poor results from successful recon missions were mainly the result of poor training and a lack of stealth. They envisaged mixed scouting units, motorcycles, HMMWVs and M3 Bradleys instead but as a validation of Deal’s idea they eventually found that HMMWV only platoons for scouting were “the most effective, least costly, and most sustainable organization”. Consequently, the US Army equipped its heavy maneuver battalions with HMMWV-based scout units although this had not been fully implemented by the time of the 1990 Gulf War with scouting being done in the main by the M3 Bradley instead.
When they were used, the small size (compared to the M113 and M3 vehicles) avoided unnecessary contact with the enemy but when it did encounter enemy forces “HMMWVs generally did not survive chance encounters with hostile elements” something not the case with the M3 Bradley.
Neither solution was suitable therefore and subsequent fighting in Afghanistan and in Iraq showed the vulnerabilities of a scout HMMWV yet further. The poor survivability of the HMMWV apparent after the invasion of Iraq prompted the Armor Center to host a ‘General Officers’ Reconnaissance Integrated Concept Team’ meeting in 2005, where it was found that regardless of armor, the HMMWV was an inadequate scout vehicle, even in its heavily uparmored M1114 form.
Work conducted at the National Training Center prior to and subsequent to Lt. Deal’s 1990 concept showed that adding more armament to the scout was also a bad idea. More armament meant engagements were more likely and during simulations “too often, scout platoons became engaged in combat and were destroyed”. Either the scout is small enough to avoid contact or it is well protected and armed enough to survive contact. The HMMWV was neither. This point is summed up well in 1991 by 1LT. Gameros who said in comparison to the M3 and HMMWV that “the M3 is not as vulnerable to enemy fire, the Bradley can serve as a fighting screen, the HMMWV cannot…[while] .. the M966 [HMMWV] is a better enemy finder.. the M3 is a better enemy fighter”.
The HMMWV then would have made a decent scout, small, mobile, and easily deployable up to the point of contact. When the shooting starts the HMMWV consistently showed itself to be a poor choice for survivability. Adding significant firepower and armor to the HMMWV then for scout use ironically makes it less survivable, just too vulnerable. The US military is currently left with Scout HMMWVs and M3 Bradleys still for its scouting role and has not yet found an adequate halfway house between the two for the role. Lt. Deal’s idea was one of many at the time to make use of the mobility of the HMMWV but sadly owed more to WW2 era thinking, best suited to wide open deserts than to a modern war or counter-insurgency operation often in complex urban environments.

Specifications
Crew	3 (4) – Commander, (Driver), 2 scouts
Armor	kevlar panels and shutters
Armament	Mk.19 Automatic Grenade Launcher/M2HB .50 cal. heavy machine gun, 2 x M60 7.62mm machine guns, Dragon AT system, smoke grenade launchers

Sources

Armor Magazine Jul/Aug 1989
Armor Magazine Nov/Dec 1990
Armor Magazine Sep/Oct 1991
Armor Magazine Mar/Apr 2007

United States of America (1979-1983)
Light Utility Vehicle – 12+ Built

The desire for a large and valuable contract for thousands of vehicles spurred many companies to try for the XM966 Combat Support Vehicle Program in 1977. TACOM (Tank Automotive Command) had issued the requirement for a vehicle capable of good off-road performance and yet still fulfill the needs of the military for general duties from hauling supplies to scouting. Of the many firms applying this contract, one was AM General.
AM General had already been the destination contractor back in 1974 for FMC (Food Machinery and Chemical Corporation) for their XR311 prototype light scout vehicle. That vehicle was more of a ‘dune-buggy’ than a practical military vehicle and if FMC had received orders from the military it was to have been AM General who built the vehicles. As it happened, no orders were forthcoming and FMC withdrew from wheeled vehicle work, selling all of the rights for the XR-311 to AM General. Thus, when TACOM announced the XM966 CVSP, AM General was in the fortunate position of not just having a design but one which the Army had already looked at between 1971 and 1975 and had liked. It is no surprise therefore that the vehicle design submitted to the military by AM General was very similar to the XR-311.

AM General Prototype. Source: unknown
The XR-311 had been a capable off-road but with some deficiencies in several areas. Firstly, it was too small, seating just 3 men at most. AM General, therefore, increased the seating to 4-5 seats by moving the seating area forwards and backward a little to make space, resulting in a vehicle looking like the XR-311 but a little ‘stubbier’. The split screen windscreen of the XR-311 was replaced with a futuristic looking 3 piece windscreen. The wheelbase was extended by 254mm and widened by 5.5cm and the height lowered by 11 cm compared to the original XR-311.
The engine was a Deutz F8L 610 V8 air-cooled (no radiator) diesel engine as the 1977 CVSP requirement had changed in 1979 to the HMMWV which required a diesel engine rather than the petrol engine of the original design. This engine was unusual in that it was air cooled but this reduced the overall weight and the number of parts which could break, thus it was simpler to maintain. It delivered 160 bhp @ 3200 rpm. This engine was coupled to the same Chrysler A727 3 speed automatic transmission as with the other designs.
Just like the XR-311 years before, examples were fitted out for a variety of roles and evaluated at Fort Knox in Kentucky with the carrier variant protected by kevlar panels. Weapons options offered included a .50 cal. heavy machine gun, 106mm recoilless rifle and TOW missile launcher with an optional kevlar armor kit.

Illustration of the AM General XM966 HMMWV Prototype produced by Andrei ‘Octo10’ Kirushkin, funded by our Patreon Campaign.

End of the line

In 1981, TACOM finalized the specifications for the HMMWV but nothing more is known of the revamped XR-311 after the 1979 requirement as attention switched to the newly designed HMMWV vehicle and the XR-311 was finally consigned to history. It is this vehicle, essentially a fourth generation of the XR-311 which was submitted by AM General that got them started and why many people see the XR-311 as the grandfather of the HMMWV although, in reality, the vehicles were quite different. The XR-311 was over in 1979, AM General was to concentrate on their own vehicle instead.

The AM General revamped XR-311 with a new, longer crew compartment. The windscreen is also now vertical but the XR-311 lineage is still very clear. Source: Bill Munroe

Specifications
Dimensions (L-w-H)	4.71 x 1.99 x 1.43 meters
Crew	1 + 4 (Driver and four passengers)
Propulsion	6.6 litre Deutz F8L 610 V8 air cooled OHV diesel producing 160 bhp @ 3200 rpm
Other specification as XR-311

Sources

HUMVEE, Bill Munroe
Wheels and Tracks #4
Armor Magazine September-October 1990