In automobile design, a rear-engine design layout places the combustion engine in the rear of the vehicle, behind the rear axle. In its most successful application, in the Volkswagen Beetle and the Porsche 911, the rear engine was combined with air-cooling for light weight, and a flat engine "Boxer" layout to reduce length and lower the center of gravity both of the engine and of the car.
Rear-engined vehicles almost always have a rear-wheel drive car layout, but some are four wheel drive. This layout has the following features:
- Packaging: since there is no need for a transmission tunnel, the floor can be flat.
- Rear traction: having the engine located over the driven wheels increases downward pressure, which is helpful for grip on loose surfaces, although can be prone to oversteer.
- Simplicity of manufacture: the engine is near the driven wheels, and the transmission can be merged with the differential to save space.
This layout was once popular in small, inexpensive cars and light commercial vehicles. Today most car makers have abandoned the layout although it does continue in some expensive cars, like the Porsche 911. It is also used in some racing car applications, low-floor buses, coach buses, Class A motorhomes, front-discharge cement mixers, some Type-D school buses, and microcars such as the Smart Fortwo. Some electric cars feature both rear and front motors, to drive all four wheels.
