The Hummer H1 is a civilian off-road vehicle based on the M998 Humvee, which was created by AM General. The vehicle was produced from 1992 through 2006, and was the first of what became the Hummer line. It was initially known only as the "Hummer"; however, in 1999 in a joint venture between General Motors and AM General, GM began marketing the Hummer H2, which was built on a heavily modified GMC 2500HD chassis. It was at this point that the original Hummer was given the H1 designation. For collectors, the most desirable model is the H1 Alpha, produced in the final model year of 2006. It had the most powerful engine and the best fuel mileage of the H1 vehicles. Overall, the H1 was a very limited production vehicle.