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Your Car: Car Terms and Definitions

Automotive terms are often thrown around as though everyone knew what they meant.

When you read car reviews or deal with salespeople and mechanics, knowing the definitions of some commonly used words can be a help. Here's a selection.

  • Wheelbase is the distance between the center of the front axle and the center of the rear axle. It's usually expressed in inches. The Chevrolet Suburban, a truly jumbo passenger vehicle, has a 130-inch wheelbase. A merely big auto, the Lincoln Town Car, has a wheelbase of 118 inches, while a small one, Toyota's Echo, has a 93.3-inch wheelbase.
  • A Monroney label, also called a "sticker," is posted on the window of a new car to provide such information as the manufacturer's suggested retail price (the MSRP, or "sticker price"), a list of options included in the vehicle, the transportation charge, and other information. It's required by a federal law that was sponsored by Rep. Mike Monroney of Oklahoma.
  • Displacement is a way of expressing engine size. It's a measure of the total volume of all the cylinders and usually is given in cubic centimeters or liters. Occasionally you hear the premetric "cubic inches" or "CID" (cubic inch displacement) used. Sometimes you'll see the engine displacement number posted in chrome on a car's exterior. In passenger cars, a 5.0-liter engine is big (a 5.3-liter is standard in the Chevy Suburban), and a 1.5-liter engine, such as in the Toyota Echo, pretty small.
  • Valves let a mixture of air and fuel into a cylinder and allow exhaust gases to get out. Each cylinder has at least two. Multivalve engines have more, often four per cylinder.
  • Jump start and kick start in their metaphorical sense are synonyms that describe any means of getting something off to a fast start. Literally, you jump-start a car that has a dead battery by connecting it to a good battery, often in another car, just long enough to start the engine. You kick-start a motorcycle by stomping down on a lever
  • VIN, an acronym for "vehicle identification number," is usually followed by "number," a redundancy hallowed by custom. It's a string of 17 digits and letters posted on the driver's side dashboard, where it can be seen from outside the car. Each VIN number is unique and contains a code that gives considerable information about the vehicle, including country of origin, manufacturer, and model year. The VIN system in its current form has been in use since the 1981 model year
  • An ABS (antilock braking system) prevents wheels from locking under heavy braking by sensing when a wheel is about to lose traction and pulsing brake pressure just enough to prevent it. This helps preserve maneuverability and may shorten stopping distance.
  • Greenhouse gases in the atmosphere absorb heat and warm up other atmo-spheric gases around them. According to the Environmental Protection Agency, Earth's atmosphere contains both naturally occurring and man-made greenhouse gases. Among them are methane, nitrous oxide, ozone, carbon dioxide, and water vapor. Human activities, such as burning gasoline in cars, add to these gases, especially carbon dioxide. The result appears to be the presence of more heat-absorbing gas in the atmo- sphere than would otherwise be there. This is believed by many to contribute to global warming.
  • MacPherson struts are a suspension system that combines a coil spring and a shock absorber in one unit. They're often used in front-wheel-drive cars because they're compact and provide for independent suspension. The name of the patent holder, Earl MacPherson, has been attached to this invention since it went into production in the early 1950s.
  • Engine speed is measured in revolutions per minute of the crankshaft and isn't necessarily related to how fast the car is going. The crankshaft of an idling engine may be turning at about 700 revolutions per minute. A comfortable, efficient operating speed for many car engines is around 2,500 rpm. Some cars have a tachometer on the instrument panel to display engine speed.

This article was first published in July 2002. Some facts may have aged gracelessly. Please call ahead to verify information.