In automobile design, a rear-engine design layout places the engine at the rear of the vehicle. The center of gravity of the engine itself is past the rear axle. This is not to be confused with the center of gravity of the whole vehicle, as an imbalance of such proportions would make it impossible to keep the front wheels on the ground. Rear-engined cars are almost always rear wheel drive, a layout known as RR. The exception is certain high performance four wheel drive models from the German automaker Porsche. This layout is chosen for three reasons - packaging, traction, and ease of manufacture:

• Since the engine is located at an extremity, the rest of the vehicle can be used for passengers and luggage.
• Having the engine located over the driven wheels increases downward pressure, which is helpful for grip on loose surfaces.
• The drivetrain can be assembled as a unit and installed easily at the factory - easier than a front wheel drive layout where the driven wheels also steer the car.