Someone who turns into an asshole when they think they are wasting gas. The opposite of a gas guzzler.
He said he didn't want to waste gas giving me a ride to my friends house, he asked me why they couldn't pick me up, he's such a gasshole.
Someone who slams on the gas to pull in front of - or purposefully obstruct - you or someone else.
Whoa! That gasshole just cut in front of me.
That gasshole just blocked me from changing lanes.