Recuperation is the capture and re-use of waste energy during braking, to reduce overall energy usage and therefore improve fuel consumption.

In electric and hybrid vehicles, regenerative braking is used to capture energy using motor/generators.

Another form of recuperation is smart control of battery charging, as used by BMW, Audi and other manufacturers. Under normal running, the alternator is disengaged and electrical equipment is run from the car's battery. The alternator is re-engaged when the vehicle is braking, slightly increasing engine braking and converting some of the vehicle's kinetic energy into electricity. This type of system is sometimes known as a micro hybrid.

Regenerative braking captures energy during braking which would otherwise be wasted, so that it can be reused later. This reduces overall energy usage.

A moving object like a car has kinetic energy propotional to its mass and the square of its speed. Power from the engine accelerates the car and generates this kinetic energy. Braking systems slow a car by converting that kinetic energy into heat energy in the brake discs and pads (or drums and shoes). This heat is lost to the atmosphere. So whenever the brakes are used, energy which has been generated by burning fuel is lost.

Regenerative braking aims to convert some of the kinetic energy into a form which can later be re-used to propel the vehicle.

In electric and hybrid vehicles, the electric motors operate as generators during braking. This provides some mechanical resistance which assists in slowing the car, and at the same time generates electricity which may be used to charge the vehicle's traction battery, or it may be stored in a bank of capacitors or a high-velocity flywheel (like the Williams system used by Porsche).

Regenerative braking is used in Formula 1 cars as part of the Kinetic Engergy Recovery System (KERS).

The running gear of a vehicle consists of the suspension, brakes, wheels and tyres - the components required for the vehicle to run along the road.

These components are now often grouped under the heading of chassis.

DTM Mercedes on a rumble strip

Rumble strips are raised kerbs used on race tracks to mark the edge of the circuit.

They are called rumble strips because their ribbed surface vibrates the car as it drives over them, setting up a rumbling sound and sensation which the driver hears and feels.

ROM Read only memory

RON Research octane number

RPM Revolutions per minute

RWD Rear wheel drive