The Hummer H1 is a civilian off-road vehicle directly based on the military M998 Humvee, produced by AM General from 1992 through 2006. It features a 16-inch ground clearance and a Central Tire Inflation System (CTIS). Most models are powered by heavy-duty V8 diesel engines, culminating in the 2006 "Alpha" version which utilized a 6.6L Duramax turbo-diesel