The size of a car's fuel tank represents the combined result of the car's fuel efficiency and the general standard that it travel between 350 and 400 miles on a single tank of fuel. The great variety of vehicles on the road causes a great variety of gas tank sizes.
Since they are smaller and therefore get better mileage, subcompact cars' gas tanks usually only hold 10 to 13 gallons of gasoline—enough fuel to propel them 350 to 400 miles.
Mid-Size Fuel Efficiencies
Mid-size cars usually require 15 to 18 gallons of fuel to allow them to travel 350 to 400 miles on a full tank because they are heavier and less fuel efficient than subcompact vehicles.
Full-sized automobiles have gas tanks with a capacity of about 18 to 20 gallons, and SUVs, which don't offer good gas mileage, usually hold 20 to 30 gallons of gasoline.
Average Tank Size
Because we drive many types of cars , and these have different efficiencies and so require various amounts of fuel to travel 350 to 400 miles, the average fuel tank holds around 15 to 18 gallons.