Why can a 50-liter fuel tank hold 55 liters of fuel?

[OIker]

The standard capacity of a car's fuel tank does not equal its actual capacity. Here are some relevant details: 1. Safety considerations: Since gasoline is volatile and expandable, for safety reasons, fuel tanks are designed to be 5%-10% larger than their standard capacity. This is why sometimes the fuel dispenser may show a higher volume than the theoretical tank capacity when refueling. However, for safety, it's advisable not to fill the tank to the brim. 2. Fuel tank types: Fuel tanks can be divided into open and closed types. A fuel tank must have sufficient volume; the suction and return pipes should be inserted below the minimum liquid level to prevent air suction and splashing that may create bubbles. To maintain oil cleanliness, the tank should have a sealed cover with an air filter. Adequate attention should be paid to the anti-corrosion treatment of the tank's inner surface.