High-Mobility Multipurpose Wheeled Vehicle
Ubiquitous in the United States Army are many variants of the High-Mobility Multipurpose Wheeled Vehicle (HMMWV), normally called the "Humvee", or sometimes the "Hummer", although the latter is a commercial, street-legal version. The HMMWV are light trucks that complement the Heavy Expanded Mobility Tactical Truck, and the new MRAP mine-protected vehicle.
Humvee variants include:
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|M1038||Cargo/Troop Carrier, with winch|
|M1044||Armament carrier, with winch|
|M1045||BGM-71 TOW carrier (Tube-launched, Optically tracked, Wire-guided missile)|
|M1046||TOW Carrier, with winch|
|M997||Ambulance, basic armor 4-Litter|
|M1042||Shelter Carrier, with winch|
|M1097||Heavy HMMWV (payload of 4,400 pounds)|
Each of these can have variant loads, and the entire series is being improved. The Armament Carrier versions have an interchangeable mount for a .50 caliber M2 machine gun, a 40mm automatic grenade launcher or a BGM-71 TOW guided missile; the TOW was designed for antitank use but can be used against buildings and fortifications.
HMMWVs, which first entered service in 1985, were developed during the Cold War when improvised explosive devices (IEDs) similar threats to non-combat were not a major concern. None of the vehicles, in fact, were designed to stop a full-power rifle bullet, although the ambulance and armament carrier had fragment protection. 
IEDs have far more power than a rifle bullet. Adding armor to a vehicle not designed for it has presented problems in the field; the engine, suspension and cooling are not designed to carry the weight of the additional protection. In some cases, it also makes the vehicle top-heavy and more dangerous to maneuver. Cooling is of special concern in environments such as Iraq.
With more than 50% of the Army’s total tactical wheeled vehicle fleet nearing the end of its useful life, a successor may be needed, although the HMMWV is still in production. One option is a more survivable variant, the Mine-Resistant, Ambush-Protected (MRAP) vehicles, now deployed in Afghanistan. These have more purpose-built protection than HMMWV's "up-armored" in the field.
At present, the Army and Marines may be continuing HMMWV production for low-risk missions, producing the MRAP, and developing the new JTLV. Even with the potential of large export sales, questions have been raised about the need for three programs.
- AM General, A Word About Armor Protection
- Feickert, Andrew (August 28, 2008), "Joint Light Tactical Vehicle (JLTV): Background and Issues for Congress", Congressional Research Service, CRS Order Code RS22942