What part of a car is measured by a device called an odometer?

An odometer measures the distance traveled by a vehicle. In a car, its reading normally records the total distance covered over the vehicle’s lifetime, usually in miles or kilometres.

Traditional mechanical odometers used gears connected to the vehicle’s wheels or transmission. As the wheels turned, the gears advanced numbered drums. Modern cars generally use electronic sensors and a digital display, but the basic purpose remains the same: converting wheel rotation into an estimate of distance.

An odometer is different from a speedometer, which shows how fast the vehicle is moving, and from a fuel gauge, which indicates the amount of fuel remaining. Many cars also have a trip meter, sometimes called a trip odometer. Unlike the permanent odometer, a trip meter can be reset to measure a particular journey or interval.

Readings can be affected by tire size, tire wear, or incorrect inflation because many systems calculate distance from wheel rotations.