Why is the car fuel tank capacity different from the actual capacity?

[WilliamAnn]

A car's 50-liter fuel tank can actually hold between 50 to 55 liters. The 50-liter capacity is usually the rated capacity stated in the car manual, which is the maximum safe capacity set by the manufacturer when the fuel tank leaves the factory. The car fuel tank capacity is smaller than the actual capacity because fuel is a flammable liquid. Filling up to the rated capacity effectively prevents overfilling and avoids spillage that could lead to fire hazards. During the actual refueling process, the amount of fuel may exceed the marked volume. This is because the volume specified by the car manufacturer is measured from the bottom of the tank to the safety limit, and there is still some space from the safety limit to the tank opening. This space ensures that the fuel can expand when the temperature rises without overflowing the tank. If fuel is filled up to the tank opening during refueling, the actual amount of fuel will exceed the marked tank volume. If the owner wants to know the remaining fuel level, they can observe the fuel gauge on the right side of the dashboard, which is marked with E and F. When the pointer is close to E, it means the fuel is almost empty, and when it is near F, it indicates sufficient fuel.