a six-speed (four forward, two reverse) Allison X-1100-3B Hydro-Kinetic automatic transmission. This gives it a governed top speed of on paved roads, and cross-country. With the engine governor removed, speeds of around are possible on an improved surface. However, damage to the drivetrain (especially to the tracks) and an increased risk of injuries to the crew can occur at speeds above . The tank was built around this engine and it is multifuel-capable, including diesel, gasoline, marine diesel and jet fuel (such as JP-4 or JP-8). By 1989, the Army was transitioning solely to JP-8 for the M1 Abrams. For logistical simplicity, JP-8 is the U.S. military's universal fuel powering both aircraft and vehicle fleets. The Australian M1A1 AIM SA burns diesel fuel, since the use of JP-8 is less common in the Australian Army. The gas turbine propulsion system has proven quite reliable in practice and combat, but its high fuel consumption is a serious logistic problem. The engine burns more than 1.67 US gallons per mile (392 Liters/100 km) or ( per hour) when traveling cross-country and per hour when idle. The high-speed, high-temperature jet blast emitted from the rear of M1 Abrams tanks makes it hazardous for infantry to take cover or follow behind the tank in urban combat. The turbine is very quiet when compared to diesel engines of similar power output and produces sound significantly different from a contemporary diesel tank engine, reducing the audible distance of the sound, thus earning the Abrams the nickname "whispering death" during its first Reforger exercise. The Army received proposals, including two diesel options, to provide the common engine for the XM2001 Crusader and Abrams. In 2000, the Army selected the gas turbine engine LV100-5 from Honeywell and subcontractor General Electric. The new LV100-5 engine was lighter and smaller (43% fewer parts) with rapid acceleration, quieter running, and no visible exhaust. It also featured a 33% reduction in fuel consumption (50% less when idle) and near drop-in replacement. The Common Engine Program was shelved when the Crusader program was canceled. Phase 2 of Army's PROSE (Partnership for Reduced O&S Costs, Engine) program, however, called for further development of the LV100-5 and replacement of the current AGT1500 engine. An Auxiliary Power Unit (APU) was designed by the Army's TARDEC, replacing an existing battery pack that weighs about . It uses a high power density Wankel rotary engine modified to use