It occured to me that having a glossary of automotive terms here may be of some use. I will add to this as necessary (currently in progress). Definitions have been taken from the Road And Track Automotive Dictionary, and/or the Bentley MINI Cooper Service Manual.
CATALYTIC CONVERTER (cat) - An emission control device in the exhaust system, usually containing platinum or palladium as a catalyst for chemical reaction of unburned hydrocarbons and carbon monoxide. It converts them into water vapor, carbon dioxide, and other gases less toxic tha untreated exhaust.
DOUBLE-CLUTCH - A driving technique, usually associated with racing, in which the driver depresses the clutch pedal, moves the shift lever out of gear into the neutral gate, releases the clutch pedal about halfway while simultaneously using the throttle to increase engine speed, then depresses the clutch pedal again while shifting to the desired gear. The purpose is to minimize gear clash or grinding, especially with transmissions using unsynchronized gears. Double-clutching can be done while shifting up or down, but is usually executed using a heel-and-toe technique during downshifting.
DTC - Diagnostic Trouble Codes
DYNAMOMETER - A machine for measuring the horsepower and torque of an engine.An engine dynamometer measures power delievered to the flywheel; a chassis dynamometer measures power delivered to the drive wheels. Sometimes shortened to dyno.
ECU - (Engine Control Unit -or- ECM: Electronic Control Module) - Computerized controls for the engine or transmission and often for the interaction between the two, and for systems such as antilock braking, air bags, and traction control.
FIXED CALIPER - A caliper on a disc brake that remains stationary relative to the disc and has a piston or pistons on both sides of the disc; the pads move inward to clamp the disc from both sides.
FLOATING CALIPER - A caliper on a disc brake, with piston(s) only on one side of the rotor - generally, the caliper has only one piston. When the brakes are applied, the piston pushes the pad on one side and pulls the pad on the other to clamp the disc; the caliper moves or "floats" along a shaft. Also called a sliding caliper.
HEEL-AND-TOE - A driving technique in which the driver places the left side or the toes of the right foot on the brake pedal and the right side or heel of the right foot on the throttle pedal so as to simultaneously brake and "blip" the throttle for a downshift. This is done to lessen the strain on the drivetrain, particularly the clutch and gearbox, and allows smoother downshifting.
HORSEPOWER (HP) - A unit of measure of power or the rate at which work is done. In the United States, where work is generally expressed in ft-lb, one horsepower is equal to 550 ft-lb/sec or 33,000 ft-lb/min.
NEUTRAL STEER - Steering characteristics in which the slip angles generated at the front and rear are identical. When such a car exceeds the limit of adhesion, the front and rear tires break loose at the same time and the car slides sideways. While this might seem to be the ideal state of balance, in reality a car with mild understeering tendancies is more stable to drive and less "nervous" than one with neutral steering characteristics.
OBD - On Board Diagnostics
OVERSTEER- A handling characteristic in which less steering lock is applied as a car speed increases around a constant-radius turn. In the oversteering condition, the rear tires are the first to slide because the rear tires turn at larger slip angles than the front. Race drivers will say an oversteering car is "loose" because the rear end tends to swing wide.
SAE - Society of Automotive Engineers
STABILIZER BAR (anti-roll bar) - A transverse bar linking both sides of a suspension system; generally, a torsion bar with rubber bushings mounted on the chassis that allow it to turn freely. The bar's ends are connected to or shaped as lever arms, with attachments to the suspension linkages at each side via ball-joint links, rubber-bushed pivot links, or, on race cars, spherical rod ends called Heim joints. When both wheels take a bump equally, the wheels move the same amount without twisting the anti-roll bar. Individual wheel movement or body roll will force the bar to twist as the lever arms are variously moved, thereby adding the bar's own spring rate to that of the car's springs. Although an anti-roll bar's main function is to reduce body roll in cornering, it also influences overall handling. Installing or enlarging a front anti-roll bar tends to increase understeer; fitting or enlarging a rear bar increases oversteer tendencies. Also called stabilizer bar or, erroneously, sway bar and anti-sway bar.
TIRE ASPECT RATIO - The ratio of a tire's cross-sectional height to its width, usually used with the expression "series". The lower the number, the lower the tire profile. Thus, a 50-series tire (section height of 50 percent of width) has a lower profile than a 60-series tire.
TIRE RATINGS - The numbers and letters imprinted on the sidewall of a tire which list such things as load capacity, size, speed capability, and tire type. For example, a P215/60VR15 tire is a metric tire with a cross section width of 215 millimeters, an aspect ratio of 60, a V speed rating, of radial construction, and with a wheel diameter of 15 inches.
TIRE SPEED RATING - Alpha value indicating a new tire's maximum speed capability. Z was initially 149+ MPH. This has since required redefining; H = 130MPH, V=149MPH, W=168MPH, Y=186MPH
TORQUE - Turning or twisting effort, usually measured in ft-lb or Newton-meters. It differes from work or power in that torque does not necessarily produce motion. The torque acting on a body is the product of the magnitude of a force arm (the perpendicular distance from the body's axis of rotation to the line of action of the force). This product is called the moment about this axis, or the torque.
UNDERSTEER - A handling characteristic in which additional steering lock is required as speed increases around a constant radius turn. An understeering car breaks away at the front end first because the front tires run at larger slip angles than the rear tires; also called "push". A characterization usually attributed to race drivers is that cars that understeer go through the fence nose first, and cars that oversteer go through tail first.
WHEEL OFFSET - The lateral distance from a wheel's vertical center plane to its mounting hub. If the wheel's center plane is outboard of its mounting hub, offset is said to be positive; if it's inboard, offset is negative.