Nowadays you can simply stop at the gas station but I'm assuming they didn't have many of those back then
Hey, take a look at these previous answers on the same topic while you're waiting:
How long after the advent of the automobile in the U.S. were filling stations common? How did people fill their tanks prior to this time? by /u/MrDowntown
How long did it take for gas stations to be common enough for a car to be a viable option for the average American? by /u/fuck_communism