Here is one answer I found: According to the American Petroleum Institute the gas-pump hose typically retains about one third of a gallon of fuel. Read more http://www.kgbanswers.com/how-much-gas-is-left-in-the-hose-after-you-are-done-pumping/4878609#ixzz2YGQfMlmO Regards, Guy Brandes 65 VAIR 140