Airbags
Bags placed around the cabin, usually tucked into panels in the dashboard or within the steering wheel, which rapidly inflate with nitrogen gas to provide a cushion between you and the car's hard surfaces in a crash.
Anti-lock brakes (ABS)
ABS stops excessive pedal pressure from locking the wheels during panic braking. Enables you to brake and steer at the same time and can radically reduce stopping distances, especially in the wet. A must-have safety item, now standard-fit on all new cars sold in the EU.
Carbon dioxide (CO2)
Carbon dioxide is a waste product of the breathing process - for cars as well as living organisms. It's a so-called greenhouse gas, a contributor to global warming. A car's carbon dioxide output is the criteria by which road tax is charged - the less it emits, the less annual road tax or, if applicable, company car tax, you'll pay. Measured in g/km - grams per kilometre.
Cruise control
A device that keeps the car at a selected speed, until the brakes are applied or you hit the accelerator; set or deactivated via a button or lever on the steering wheel.
ESP (electronic stability control)
An electronic system, usually integrated into the ABS, that monitors yaw (the angle and direction in which the vehicle is travelling) and the steering wheel angle to assess stability. If it detects that the car is skidding or becoming unstable, it then cuts the throttle or applies braking pressure to individual wheels to re-establish control. ESP is particularly important in vehicles with a high centre of gravity, such as 4x4’s.
Four-wheel drive
In a four-wheel-drive vehicle, power is supplied to both the front and rear axles, though not necessarily all the time. Some systems have full-time four-wheel drive, with power sent in a fixed ratio to both front and rear pairs of wheels; others have a part-time or 'torque on demand' system, where power goes to one axle (front or rear) unless a loss of grip is detected, with power then automatically sent to the axle with the most traction. Many high-performance cars with four-wheel drive have sophisticated systems that can automatically divide the power around all four wheels continually, according to which wheel has the most grip on the road. Alternatively, some 4x4s are front- or rear-wheel drive for normal road use, but the driver can select four-wheel drive to go off-road.
Isofix
A standardised system of fixing points to anchor child seats into a car. Now standard in most family cars and other models, it enables the safe use of compatible child seats.
Pre-tensioning seatbelts
Belts designed to take up the slack and grip the body more tightly when sensors anticipate a crash, thus limiting the distance you can be flung forwards or jerk backwards again.
Quattro
Audi's patented all-wheel-drive system.
RPM (revolutions per minute)
The number of times the engine's crankshaft rotates in a single minute. The harder you press the throttle, the higher the rpm, depending on which gear you're in. The rpm rate is usually governed by a rev limiter so you can't push your car over the redline (its maximum rev limit) and blow its engine up.
Sat nav
Satellite navigation. Uses a sophisticated locator device that takes a 'fix' on the car's position, speed and direction of travel from satellites above the Earth. Linked to a CD or DVD of maps, the system can then direct you, road by road, to your desired destination.
Supercharger
A mechanically driven turbine that boosts engine power by forcing compressed air into the cylinders. As used in the Mini Cooper S, or in many Mercedes models, where it is known as a Kompressor. Thought to give a smoother power delivery than a turbocharger.
Traction control
A device that detects wheelspin and cuts power or applies pulse braking to the offending wheel in order to regain grip, or traction
Torque
The turning or twisting force imparted on the driveline by the engine, also known as 'pulling power', it indicates an engine's strength and flexibility (i.e. the ability to pull in each gear) rather than its power and overall speed. Normally measured in lb-ft or Newton Metres (Nm). Big torque figures at low revs are a feature of large V8s, while high-revving four-cylinder engines normally have lower torque at higher revs. Diesels typically develop their maximum torque low-down the rev range.
Turbocharger
Forces compressed air into the engine with a turbine; like a supercharger, but driven by exhaust gases rather than the crankshaft. The delay common in early turbocharged cars between pressing the throttle hard and achieving acceleration is known as 'turbo lag'.
Xenon headlamps
Electricity is used to ignite plasma gas inside the sealed headlamp casings, creating a bluish-toned light many times brighter than a normal bulb. Also known as 'gas-discharge' lamps.
