Many emissions systems include an air pump, which pumps fresh air into a vehicle's exhaust to help complete the combustion process and reduce emissions.

The ratio of air to gasoline in the fuel mixture drawn into the engine.

An aerodynamic device designed to improve traction by increasing the down force on the car. The use of airfoils (also called wings) increases the cornering capability and improves stability at speed, but often at the expense of additional aerodynamic drag.

It is the proper adjustment of the car's front and rear suspension for camber, toe, caster and ride height. Alignment is when all your wheels are pointing in exactly the right direction. If one wheel is off by even one or two degrees, it is considered out of alignment. When a vehicle is out of alignment, excessive tire, steering system and suspension system wear may be the end result.

Often confused with Four-Wheel Drive (4WD), this drive system features four, full-time active drive wheels to reduce wheel slippage and provide greater driver control over the vehicle. AWD automatically splits engine torque between the front and rear wheels as needed, improving on-road traction in unfavorable road conditions. Unlike Four-Wheel Drive, AWD is an on-road system and is not designed for off-road use. AWD does not require the driver to actively engage the system. It is operational at all times, and requires no switches, lights or visor instructions for system operation.

A generic term used to describe any non-steel road wheel. The most common alloy wheels are cast aluminum. Technically, an alloy is a mixture of two or more metals. These wheels are known for their light weight and strength. Alloy wheels are less prone to corrosion and can be significantly lighter than the equivalent steel wheels.

An alternator is an engine accessory that generates electricity to keep your battery charged, and operate your vehicle's electrical system. It converts rotational energy to AC current. It produces alternating current (AC) for the car by spinning a magnet inside a stationary conductor.

Regulations requiring vehicle manufacturers to include content information on vehicle labels for cars and trucks for sale in the U.S. after October 1, 1994.

An instrument, calibrated in amperes, used to measure the flow of an electrical current in a circuit. Ammeters are always connected in series with the circuit being tested.

The rate of flow of electrical current present when one volt of electrical pressure is applied against one ohm of electrical resistance.

Any microprocessor that uses similar (analogous) electrical signals to make its calculations.

A tuned-in front suspension characteristic that converts braking-induced forces in the suspension links into a vertical force that tends to lift the body, thereby reducing dive under braking.

System that automatically controls wheel slip or prevents sustained wheel-locking on braking. On a vehicle equipped with Anti-Lock Brakes, the wheels are equipped with speed sensors. When a sensor determines that a wheel is decelerating so rapidly that lockup may occur, the Electro-Hydraulic Control Unit (EHCU) is activated. The EHCU then modulates the brake pressure in the appropriate brake lines by means of the solenoid-operated valves. This is intended to prevent wheel lockup and help the vehicle maintain directional stability during potentially hazardous braking situations. Don't 'pump' antilock brakes in a skid, as you would with standard brakes, or they'll be less effective. (See also: Rear-Wheel Anti-Lock and Four-Wheel Anti-Lock.)

A suspension element (used at the front, the rear, or both ends of a car) that reduces body roll by resisting any unequal vertical motion between the pair of wheels to which it is connected. An anti-roll bar does not affect suspension stiffness when both wheels are deflected equally in the same direction. Often incorrectly called a sway bar. An anti-roll bar improves the handling of a vehicle by increasing stability during cornering or evasive maneuvers. Most vehicles have front anti-roll bars. Anti-roll bars at both the front and rear wheels can reduce roll further.

Similar to anti-dive, this suspension characteristic uses acceleration-induced forces in the rear suspension to reduce squat.

Many modern radios have special anti-theft circuitry that prevents them from operating after being disconnected from a power source. For these types of radios, it is necessary to enter a factory-supplied code to get the radio to work again.

The fluid mixed with water that is put into your vehicle's radiator. Antifreeze is traditionally green in color; however, newer long-life antifreezes may be red or orange. Please refer to your vehicle's owner's manual for the proper antifreeze for your vehicle.

The point(s) or region on the line through a corner that touches the corner's inner radius.

A laminated, soft iron core wrapped by a wire that converts electrical energy to mechanical energy as in a motor or relay. When rotated in a magnetic field, it changes mechanical energy into electrical energy as in a generator.

Generally the ratio between two dimensions of an object. In tire terminology it applies to the unloaded sidewall height of the tire divided by its overall width. A lower aspect ratio implies a shorter, wider tire. When used to describe a wing it is the span of the airfoil (the long dimension perpendicular to the airflow) divided by its chord (the dimension parallel to the airflow).