The vertical or sometimes diagonal roof supporting member located at the extreme rear of the roof or greenhouse structure on station wagons and some sedan models.

The nineteenth-century axle principle of Count de Dion. The wheels tied by a transverse tube curved to clear the final drive unit rigidly mounted to the car's chassis frame. Drive to the wheels is by universally jointed half shafts. The tube moves vertically on a slide to allow the wheels to rise and fall independently. General use was dropped in 1914, but still is used on many sports and racing cars.

The extreme top or bottom of the piston stroke.

A footrest found to the left of the leftmost pedal. It provides a place for the driver to brace his left leg during hard cornering.

A firm that buys and sells, adding some value for the consumer in the process. Dealer often means a firm which operates closer in the distribution channel to the consumer than a distributor or wholesaler, and may add more value for consumers than either of the above-mentioned terms.

The amount of an insurance claim that is paid by the insured before insurance payment begins.

A setting of your car's heating controls that lets you easily remove frost and fog from your vehicle's windows.

A condition in which, after the spark plug fires, some of the unburned air-fuel mixture in the combustion chamber explodes spontaneously, caused by excess heat and compression, advanced timing, or an overly lean mixture. Detonation, or 'knock', greatly increases the mechanical and thermal stresses on the engine. Also referred to as 'ping'.

A thin, flexible wall separating two cavities, such as in a vacuum advance unit.

Solid or hollow form used for shaping materials by stamping, pressing, extruding, drawing or threading.

A diesel engine uses heavier weight components than gas engines to handle higher compression ratios. Typically, diesel engines run with greater efficiency and higher torque than similar size gas engines. These attributes lead to better fuel economy and towing performance. Diesel engines do not have spark plugs or carburetors. Instead glow plugs are used to preheat air in the cylinders to ensure easy starts. Once the engine is started, compression heats the fuel in the cylinders for combustion. Diesel engines use kerosene as fuel. Diesels are often more economical than gasoline engines; however, they create extra noise and vibration.

A condition in which hot spots in the combustion chamber cause the engine to run on after the key is turned off. A condition in which gasoline continues to fire after the ignition has been shut off. In late-model engines, dieseling, or run-on, is caused by heat and the unusually high manifold pressure that result from retarding the spark at idle. In fuel-injected cars when the engine is turned off, fuel is automatically shut off, eliminating dieseling.

A part of a car's driveline that takes the power from the engine and splits it between two wheels or two axles. A differential also lets two wheels on the same axle rotate at different speeds. For instance, when you go around a corner, the inside wheel turns slower than the outside wheel. Without a differential, cars would not be able to take sharp turns. A special gearbox designed so that the torque fed into it is split and delivered to two outputs that can turn at different speeds. Differentials within axles are designed to split torque evenly; however, when used between the front and rear axles in four-wheel-drive systems (a center differential), they can be designed to apportion torque unevenly.

The same attributes of a standard differential, except that when one wheel is slipping, the most torque is supplied to the wheel with best traction. A locking differential reduces the possibility of a vehicle becoming immobile when one driving wheel loses traction.

The way in which innovations spread through market or non-market channels.

An electrical device that will allow current to flow in one direction only.

A vehicle's ability to maintain a true course of travel despite bumps, crosswinds, uneven road surfaces.

Properly called caliper disc brakes, a type of brake that consists of a rotor that rotates at wheel speed, straddled by a caliper that can squeeze the surfaces of the rotor with brake pads near its edge. Disc brakes provide a more linear response and operate more efficiently at high temperatures and during wet weather than drum brakes. A hydraulic braking assembly consisting of a brake disc, or rotor, mounted on a axle, and a caliper assembly containing, usually two brake pads which are activated by hydraulic pressure. The pads are forced against the sides of the disc, creating friction which slows the vehicle. Used on race cars, sports cars, and better passenger cars.

In an engine, the total volume of air or air-fuel mixture an engine is theoretically capable of drawing into all cylinders during one operating cycle. Generally expressed in liters or cubic inches. Engine displacement is equal to (bore) x (bore) x (stroke) x (number of pistons) x (.785).

Synonymous with wholesalers; distributors perform many of the same functions as wholesalers, such as selling, physical distribution, credit, etc. Some industries use the term distributor instead of wholesaler.