Engine size is measured in several ways, including cubic centimeters in small engines and most motorcycles, cubic inches in most American cars and liters in most foreign cars. This isn’t a rule, however. American hot rods use liters as a measurement quite often. The size is representative of the displacement of the cylinders of the engine. Why engine displacement is displayed in specific ways is up to the manufacturer, but it often comes down to marketing which size sounds neater, bigger or more powerful.
The displacement of an engine, or the engine’s size, refers to the amount of space its cylinders take up. Often, this is measured in liters, especially for larger engines that are found in cars and trucks. An example would be the Ford Mustang’s 5.0 liter engine. It is also commonly referred to as the 302 cubic inch motor. This simply means that the cylinder space of the engine displaces 5 liters or roughly 302 cubic inches. Naturally, cars with more cylinders will typically have larger displacements.