You tell your friend he is just about out of fuel. He says not to worry; there is still a gallon [some four liters] in the tank.
Jūs ieminaties draugam, ka viņa automašīnai drīz beigsies degviela, bet draugs atbild, ka raizēm nav pamata — degvielas tvertnē vēl esot vairāki litri.