2-Wheel Drive The engine, clutch and gearbox are usually mounted on the frame at the front of the vehicle. The rotating motion produced by the crankshaft at the front of the vehicle is transmitted either to the two wheels at the rear (rear wheel drive), or the two wheels at the front (front wheel drive). Some cars are manufactured with rear mounted engines that drive the rear wheels, and front mounted engines that drive the front wheels. 4 Wheel Drive 4-wheel drive vehicles use live front and rear drive axles. When the front drive axle receives power from the transfer case, along with the rear drive axle, the vehicle can function well on off-road terrain (sand, rocks, mud, snow, etc.). A 4-wheel drive vehicle has one drive axle that is automatically in use. The operator of the vehicle has to activate and deactivate the second live drive axle. All Wheel Drive (AWD) All-wheel drive vehicles use live front and rear drive axles. When the front drive axle receives power from the transfer case, along with the rear drive axle, the vehicle can function well on off-road terrain (sand, rocks, mud, snow, etc.). A 4-wheel drive vehicle has one drive axle that is automatically in use. The operator of the vehicle has to activate and deactivate the second live drive axle. An all-wheel drive vehicle has both axles live at all times without manually activating or deactivating axles.