the engine position is once again used to increase performance and the potentially smoother ride is usually more than offset by stiffer shock absorbers. This layout also allows the motor, gearbox, and differential to be bolted together as a single unit. Together with independent suspension on the driven wheels, this removes the need for the chassis to transfer engine torque reaction. Drawbacks The largest drawback of mid-engine cars is restricted rear passenger space; consequently, most mid-engine vehicles are two-seat vehicles. The engine in effect pushes the rear passenger seats forward towards the front axle (if the engine is behind the driver). Exceptions typically involve larger vehicles of unusual length or height in which the passengers can share space between the axles with the engine, which can be between them or below them, as in some vans, large trucks, and buses. The mid-engine layout (with a horizontal engine) was common in single-decker buses in the 1950s and 1960s, e.g. the AEC Reliance. The Ferrari Mondial is to date the only successful example of a true mid-engined convertible with seating for 4 and sports car/supercar performance. A version of the Lotus Evora with a removable roof panel is anticipated but no definite date is known. Like any layout where the engine is not front-mounted and facing the wind, the traditional "engine-behind-the-passengers" layout makes engine cooling more difficult. This has been a problem in some cars, but this issue seems to have been largely solved in newer designs. For example, the Saleen S7 employs large engine-compartment vents on the sides and rear of the bodywork to help dissipate heat from its very high-output engine. Mid-engined cars are more dangerous than front-engined cars if the driver loses control - although this may be initially harder to provoke due to the superior balance - and the car begins to spin. The moment of inertia about the center of gravity is low due to the concentration of mass between the axles (similar to standing in the middle of a playground roundabout, rather than at the edge) and the spin will occur suddenly, the car will rotate faster and it will be harder to recover from. Conversely, a front-engined car is more likely to break away in a progressive and controllable manner as the tires lose traction. Variations Super, sport, and race cars frequently have a mid-engined layout, as these vehicles' handling characteristics are more important than