RPM stands for "revolutions per minute," and its the automotive industry's standardized method of measuring engine speed. It is a measure of how many times the engine's crankshaft makes one complete rotation each minute, and simultaneously, the number of times each piston goes up and down in its cylinder. The RPM gauge contains numbers with each denoting 1,000 RPM, so if a vehicle's RPM meter points to 3, then the car must be rotating at 3,000 RPM. RPM measures how fast the internal combustion engine is running at a given time. It increases when you press the accelerator while driving your car, and power increases to a certain extent with the increase in RPM. RPM is an important factor associated with cars' performance, and it affects fuel consumption while driving. RPM is directly proportional to the fuel consumption in a vehicle, so a lower RPM means less fuel consumption. In a manual car, the driver has to keep an eye on the RPM and change gears accordingly. Modern cars use a "rev limiter" to keep a car engine from "revving" too high before shifting to a higher gear.