Vehicles can be described by the number of axles. Most light vehicles only have 2 axles.
This vehicle has 4 wheels but only 2 driving wheels.
This one has 4 driving wheels, and is commonly called a 4-wheel drive vehicle.
The location of the driving axle determines whether the vehicle is classified as: rear-wheel drive, front-wheel drive, 4-wheel drive, or all-wheel drive.
Rear-wheel drive vehicles can use a conventional layout with the engine at the front of the vehicle. The torque from the engine is transmitted to the rear-mounted driving axle by propeller, or drive shaft. This spreads the weight of components throughout the vehicle.
This rear-wheel drive vehicle has the engine at the rear, driving the wheels through a combination transmission and rear axle called a transaxle. The transaxle is lighter than a separate transmission and rear axle.
Moving the engine to the rear allows a lower hood profile, which improves aerodynamics. The increase in weight over the rear wheels can improve their traction.
This vehicle has the engine located behind the operator's cabin, but forward of the rear driving axle. This is called a mid-engine, rear-wheel drive vehicle. A mid-engine design locates the engine behind the driver but forward of the rear axle. This allows for a low hood profile, and good handling.
Front-wheel drive vehicles use the front wheels to pull the vehicle along. In light passenger vehicles it gives lighter body weight, and increased interior room. The engine and transaxle are at the front, and can be mounted laterally, that is, the engine is parallel to the front axle, or longitudinally where the engine is inline with the center line of the vehicle.
