Rear-engine, rear-wheel-drive layout

In automotive design, an RR, or rear-engine, rear-wheel-drive layout places both the engine and drive wheels at the rear of the vehicle.

Placing the engine near the driven rear wheels allows for a physically smaller, lighter, less complex, and more efficient drivetrain, since there is no need for a driveshaft, and the differential can be integrated with the transmission, commonly referred to as a transaxle.

Under hard acceleration, the decreased weight over the front wheels means less traction, sometimes producing a tendency for rear-engined cars to understeer out of a corner.

Furthermore, because both axles are on the same side of the engine, it is technically more straightforward to drive all four wheels, than in a mid-engined configuration (though there have been more high-performance cars with the M4 layout than with R4).

Due to the handling difficulty, the need for more space efficiency, and the near ubiquitous use of liquid-cooled engines in modern cars, most manufacturers have abandoned the RR layout.

The major exception is Porsche, who has developed the 911 for over 40 years and has taken advantage of the benefits of RR while mitigating its drawbacks to acceptable levels, lately with the help of electronic aids.

The radical 1930s Tatra format (air-cooled, rear engine and streamlined, teardrop design) was an influence on Ferdinand Porsche's 'People's Car' (Volkswagen) for Adolf Hitler.

The final form of the RR Volkswagen was the Type 3 of 1961, which flattened the engine (or 'pancake'), allowing for luggage spaces front and rear.

Early cars using the RR layout included the Tucker, Volkswagen Beetle, Porsche 356, Chevrolet Corvair, NSU Prinz, ZAZ Zaporozhets and Hino Contessa.

Most tour buses and coaches also employ a similar design, however the free space is usually used for luggage, and sometimes air conditioning equipment.