Front-engine, front-wheel drive layout

In automotive design, an FWD, or front-engine, front-wheel-drive layout places both the internal combustion engine and driven roadwheels at the front of the vehicle.

Historically, this designation was used regardless of whether the entire engine was behind the front axle line. In recent times, the manufactures of some cars have added to the designation with the term front-mid which describes a car where the engine is in front of the passenger compartment but behind the front axle. Most pre-World War II front engine cars would qualify as front-mid engine, using the front-mid designation, or on the front axle.

This layout is the most traditional form, and remains a popular, practical design. The engine which takes up a great deal of space is packaged in a location passengers and luggage typically would not use. The main deficit is weight distribution — the heaviest component is at one end of the vehicle. Car handling is not ideal, but usually predictable.

In contrast with the front-engine, rear-wheel-drive layout (RWD), the FWD layout eliminates the need for a central tunnel or a higher chassis clearance to accommodate a driveshaft providing power to the rear wheels. Like the rear-engine, rear-wheel-drive layout (RR) and rear mid-engine, rear-wheel-drive layout (RMR) layouts, it places the engine over the drive wheels, improving traction in many applications. As the steered wheels are also the driven wheels, FWD cars are generally considered superior to RWD cars in conditions where there is low traction such as snow, mud, gravel or wet tarmac. When hill climbing in low traction conditions RR is considered the best two-wheel-drive layout, primarily due to the shift of weight to the rear wheels when climbing. The cornering ability of a FWD vehicle is generally better, because the engine is placed over the steered wheels. However, as the driven wheels have the additional demands of steering, if a vehicle accelerates quickly, less grip is available for cornering, which can result in understeer.High-performance vehicles rarely use the FWD layout because weight is transferred to the rear wheels under acceleration, while unloading the front wheels and sharply reducing their grip, effectively putting a cap on the amount of power which could realistically be utilized; in addition, the high horsepower of high-performance cars can result in the sensation of torque steer. Electronic traction control can avoid wheel-spin but largely negates the benefit of extra power. This was a reason for the adoption of the four-wheel-drive quattro system in the high performance Jensen FF and Audi Quattro road cars.

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