The M1 Abrams was the next stage in American tank development after the M60 series. Chrysler completed the prototype in 1978 and the first production vehicles appeared in 1980 with 30 tanks a month being built in the years that followed by General Dynamics, then a division of Chrysler Motors. Its advanced Chobham armour makes the M1 the best protected US main battle tank yet devised. Its gas turbine engine is smaller and easier to service than a diesel engine, but the extra fuel requirement negates the space saved, which is perhaps why the idea was rejected for acquiring the German-built Leopard 2. Thermal sights, laser rangefinder equipment, and a sophisticated gun stabilization system give the M1 excellent firepower on the move, be it day or night. In the 1991 Gulf War, the Abrams proved itself the best tank in the world, knocking out Iraqi T-72s with impunity. In fact, no Abrams were lost due to enemy fire.