Wiktionary
gas up
vb. (context transitive US slang English) To fill the gas tank of an automobile with fuel.
WordNet
gas up
v. fill with gasoline; "Gas up the car"
Usage examples of "gas up".
You pulled what might be called a Trojan suit trick, and got Saki to release gas up here.
I mean, a guy who would kill a planeload of innocent people undoubtedly had an atomic bomb up his sleeve, or anthrax in his hat, or poison gas up his ass.
George was on patrol that shift, but happened to be close by and so came in to gas up.
Several other cars got off 1-5 with her at Elaine to gas up, but that meant nothing.