A List of Automotive Terms & Acronyms

The following is an alphabetical list of automotive terms used when talking about vehicles, components, and motorsports, along with their definitions. The links will either jump to the main term/definition (often for abbreviations) or direct you to a full page about the term/component.

Navigation

Use the following links to skip to A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, and Numbers.

A

• ABS: An abbreviation for Anti-lock Braking System.
• AC: This can either be an abbreviation for Air Conditioning, or the electrical term Alternating Current.
• Acceleration: The rate in which speed increases. This is popularly measured as a 0-60 MPH time.
• Afterfire: Often mistaken for a backfire. When unburned fuel combusts in the exhaust, often causing flames to shoot from the exhaust tip.
• Aftermarket: This is a term to describe parts which are not stock. An example of might be a carbon fiber hood, or an upgraded stereo system.
• All Wheel Drive: This means all of the vehicle's wheels are being powered by the engine. It often has the same meaning as 4 Wheel Drive, unless the vehicle has more or less than four wheels.
• ASE: An abbreviation for Automotive Service Excellence, an organization that establishes & maintains standards in the auto service industry, and administers tests for automotive technicians.
• ASM: An abbreviation for Active Stability Management.
• AT or A/T: An abbreviation for Automatic Transmission.
• Automatic: Often short for an automatic transmission, such as in the phrase "I drive an automatic". However, in another context, it could mean anything that is controlled or operated by something other than a person.
• AWD: An abbreviation for All Wheel Drive.

B

• Backfire: This occurs when fuel ignites in the intake, usually due to poor valve timing. It can damage the carburetor, the throttle plates, sensors, and even cause a fire in the engine compartment.
• Belly Pan: Another name for an underbody.
• Big Block: Referring to the size of an engine block, usually an American muscle car engine term.
• Blown Gasket: Mechanic slang for a broken gasket, sometimes specifying which one it is ("On that last run we blew a head gasket.").
• Bore: The measuerment of cylinder diameter. Important when measuring displacement.
• Burn Out or Burnout: Usually done by drag racing cars to warm up the drive wheels, spewing white smoke (burned rubber) as the tires spin across the road surface while the vehicle is either stopped or moving very slowly. This is also done to show off, showing spectators that the engine is powerful enough (and the driver skillful enough) to do it.

C

• Camber: Wheel tilt into or away from the vehicle.
• CAN-BUS: A computer system called a Control Area Network, which sends digital information to and from computer systems and sensors.
• Caster: Refers to the angle and position of the pivot point for the steering wheels.
• CI: Cubic Inches, often used to measure the displacement of an engine, espeically classic American engines.
• CID: Cubic Inches of Displacement, used to convey the displacement of an engine, espeically classic American engines.
• Cold Air Intake: An intake which is designed to take in air from anywhere but the engine compartment, which is heated by the engine. Cold air is more dense, and a vehicle can get more power out of dense air.

D

• Daytime Running Lamps: Headlights which are on (at reduced power) during the day, as a safety feature.
• Displacement: ^π/₄ times bore² times stroke times the number of pistons.
• DOHC: An abbreviation for Dual Over Head Cam, an over-head cam design.
• Double Clutch: This may either refer to a type of drivetrain layout with two clutches, or the racing term which involves releasing the clutch suddenly to launch the vehicle forward, then pressing the clutch a second time to let the engine build up RPM, and releasing the clutch again. When done properly, and in the right vehicle, this can improve initial acceleration because it will use both the engine's power and momentum to accelerate.
• Drifting: A flamboyant style of driving based on controlling a car on the verge of spinning out.

E

• EFI: An acronym for Electronic Fuel Injection.
• EGR: An acronym for Exhaust Gas Recirculation.

F

• Floor Pan: Another name for an underbody, though sometimes a name for the sheet metal that makes up the bottom of a vehicle.
• Firewall: A seperation between the driver and engine, for safety purposes, though often serves as a way to increase chassis rigidity as well. It is intended to keep any engine bay fires away from the driver.
• Fuel Economy: An all-around term describing an engine/vehicle's efficency with its fuel. Also see our article on how to improve fuel economy.

G

• Ground Clearance: Referring to the amount of space between the bottom of the chassis and the driving surface, not including the wheels. It is important to know when driving over various objects and driving surface conditions.

H

• High Beams: A setting of high output level for the headlights.

I

• Indicators: Another word for turn signals.

J

K

• Kilometers Per Hour: The number of kilometers something can travel within an hour, maintaining a given speed. It is often seen abbreviated as KPH.
• KPH: An acronym for Kilometers Per Hour. See also: MPH/Miles Per Hour

L

• Lean: Referring to the air/fuel mixture, where there is too much air/not enough fuel. Opposite of a rich mixture.
• Loose: A term used by race car drivers (notably in NASCAR) to describe a condition where the rear wheels lose traction before the front wheels, causing the rear to slide more while turning.

M

• Miles Per Gallon: The number of miles a vehicle can travel under given conditions using a gallon of its fuel. This a common way to measure fuel economy, and often abbreviated to MPG.
• Miles Per Hour: The number of miles something can travel within an hour, maintaining a given speed. It is often seen abbreviated as MPH.
• MPG: An acronym for Miles Per Gallon.
• MPFI: An acronym for Multi-Port Fuel Injection.
• MPH: An acronym for Miles Per Hour.

N

• Naturally Aspirated: This describes an engine which takes in air "naturally", or without the use of a Turbo or Supercharger.
• Nitrous & Nitrous Oxide: The compound NO₂, which is 33% Oxygen and 66% Nitrogen, which contains more oxygen than normal air. It is sprayed into the intake with additional fuel to boost engine performance.
• NOS: A particular brand of NO₂ bottler/kit manufacturer which has become synonymous with Nitrus Oxide.
• Nose: The front end of a car, usually including the hood/bonnet and front bumper.

O

• OBD/OBD2/OBD II: On Board Diagnostics, in both regular and second-generation form, is a way mechanics can simplify their diagnosis work; they connect an OBD cable to the appropriate port on the vehicle (usually found under the dashboard, on the driver's side) and get fault codes, which the car's computer generates using sensor information. Many scan tools will describe the code as well.
• OEM: An abbreviation for Original Equipment Manufacturer. Also, see stock.
• O₂ Sensor: Another name for an Oxygen Sensor.

P

Q

R

• Redline: The RPM at which it becomes dangerous for the engine to run at, typically due to mechanical limitations, and often the point where a limiter cuts off fuel to the engine for a short time.
• Revolutions Per Minute: The amount of times a part rotates in the span of one minute, often referring to engine speed ("The redline is at 7,200 RPM").
• Ride Height: This can either refer to the overall height of the vehicle, or the ground clearance. Often it is used in a manner where either may work, such as in the phrase "the car needs a lower ride height".
• Rotations Per Minute: The amount of times a part rotates in the span of one minute, often referring to engine speed ("The redline is at 7,200 RPM").
• RPM: An abbreviation for Rotations Per Minute or Revolutions Per Minute.

S

• Scrap, Scrapped, or Scrapping: A slang term, referring to when a car is beyond repair (for what it's worth), and the owner sells it for the value of its working parts, or for the value of the materials which can be recycled from it.
• SFI: An acronym for Sequential Fuel Injection.
• Sleeper: Slang for a car which doesn't appear to be impressive due to looks (a low-end model, poor body condition, or a generally known slow car) but has surprising performance.
• Spin Out: When a vehicle turns much more than expected, losing control and sliding as it rotates across the driving surface. Not to be confused with a burn out or drifting.
• Small Block:Referring to the size of an engine block, and usually an American muscle car engine term.
• Stall/Stall Out: A stall out occurs when the engine doesn't have enough roational speed to keep its momentum up, and it stops running.
• Stock: A term to describe an unmodified car, or a part which the car originally came with out of the factory.
• Stroke: The distance a piston travels up and down within a cylinder.

T

• TCS: An acronym for Traction Control System.
• TDC: An acronym for Top Dead Center.
• Tight: A term used by race car drivers (notably in NASCAR) to describe a condition where the front wheels lose traction before the rear wheels, which forces them to turn at a lower speed to avoid crashing.
• Toe In/Toe Out: When wheels are bent inwards on the steering axis (in and out refer to the front of the wheels).
• Top Dead Center: Used to describe when a piston reaches the highest point in its stroke.
• Tuner: "Tuner" cars are generally street cars which have been customized for improved performance,but that isn't always the outcome.
• Tuning: This generally refers to making adjustments to a vehicle to improve its performance, sometimes for a particular track or driving route.
• Turbo:A short name for turbocharger, formerly considered slang. Sometimes falsely portrayed as something that can be activated with a button/switch.

U

• Underglow: Bright lighting which can be seen under the car, reflecting off the road. The only intent of these lights is aesthetic appeal.

V

• VIN: An abbreviation for Vehicle Identification Number.
• VVT: An abbreviation for Variable Valve Timing.

W

• Wide Open Throttle:When the throttle is pressed down all the way, and the throttle body is completely open.
• WOT: An abbreviation for Wide Open Throttle.

X

Y

Z

Numbers

• 0-60: A popular acceleration test, which measures how quickly a car can get to 60 MPH from a motionless start.
• 4WD: An abbreviation for 4 Wheel Drive.
• 4WS: An abbreviation for 4 Wheel Steering.
• 4 Wheel Drive: Used to describe a vehicle with four wheels driven by the engine. When a four wheel drive vehicle only has four total wheels, it may also be called All Wheel Drive, but the terms differ on how the systems actually work.
• 4 Wheel Steering: A steering system which uses all four wheels to steer, improving the turning radius.

If the term you were looking for doesn't seem to be here and you've double-checked, (you can press Ctrl and F at the same time to search for text words) it may be on the main page. It is possible that we may have forgotten it, however, and will add it as soon as we are informed on Twitter or Facebook. There are currently 83 items on this list.