Rear-wheel drive

In a rear-wheel-drive vehicle the engine sits lengthways at the front, the gearbox hangs off the back of it, and a propeller shaft runs under the floor to a differential on the rear axle, which drives the rear wheels.

• Torque leaves the gearbox and turns the propeller shaft, a long tube with universal joints at each end so it can flex as the body moves on its springs.
• At the rear, a small pinion gear on the shaft meshes with a large crown wheel inside the differential, turning the drive through 90 degrees and providing the final reduction.
• The differential splits torque between the two rear wheels and lets them turn at different speeds in a corner.
• Half-shafts take the drive to each wheel: inside a solid axle tube on ladder-frame SUVs and trucks, or as separate jointed shafts on cars with independent rear suspension.

The front wheels are left to do nothing but steer, so steering feel is clean and the turning circle is often tighter. Weight transfers onto the rear wheels under acceleration, which is exactly where the grip is needed when pulling a load or climbing with a full cabin.

What you notice: a tunnel down the middle of the floor, a slightly higher price and weight than front-wheel drive, and, in the wet, a rear end that can step out if you are heavy with the throttle. Mahindra's Scorpio-N and Thar, Toyota's Fortuner and Innova Crysta, and every BMW saloon are rear-wheel drive in their basic form; so is almost every truck, from the Tata Ace to a 55-tonne tractor unit.