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. In addition, even though the rear wheels benefit from the additional traction the added weight of the engine gives, the front wheels still need traction in order to steer the car effectively. For this reason, a rear-engined car can also be prone to understeer.