Based on: The Hummer, HMMWV or Humvee is an all-terrain vehicle, which was developed as a successor to the Jeep for the U.S. Army and has been produced since 1985 by the U.S. manufacturer, AM General Corporation in various versions.
On 22 March 1983 joined the United States Army with the AM General Division (now AM General Corporation) a contract in the amount of 1.2 billion U.S. dollars for the supply of 55,000 units of the High Mobility Multipurpose Wheeled Vehicle (HMMWV, pronounced Humvee short) in 15 different versions from. The U.S. Army eventually ordered 70,000 units, thereby increasing the contract value to $ 1.6 billion. This was the largest ever completed by the U.S. Army contract for the supply of military wheeled vehicles. Currently, the Marine Corps has about 20,000 Humvees, the Army more than 120,000.
The internal designation M 998 Series is the Army. It is a multi-purpose four-wheel drive vehicle with a payload of 1.25 tons. The lobster is very versatile and has a high mobility and speed. It replaced a number of obsolete light transport vehicles such as the Jeep, the Dodge M-880 pick ups, as well as the M 561 and M 274 Gama Goats Mules.
The HMMWV have been tested by the U.S. Army under the most demanding conditions, such as under combat conditions in difficult terrain, over rocky hills, by 1.50 m deep water in deep desert sand, as well as in arctic cold.
Source: Wikipedia: lobster there exist much more information to the HMMWV and its variants