While it is correctly referred to as “auto body” (two words) many people combine the word into one: autobody. Auto body refers mostly to the outside of the vehicle, the panels, trim pieces, front and rear bumper. Auto body differs from auto repair in that auto repair mostly refers to the inner workings and components necessary to keep the engine running and the car driving, Whereas auto body is mostly concerned with the outside aesthetics of the vehicle, as well as safety features.

auto body (as defined by Wiktionary)
noun
Alternative form of auto body.

autobody (according to Definitions.com)
noun
Autobody was a Brooklyn, New York based indie rock band. They released three albums on the Silly Bird label, as well as various other tapes and 7″ records. (Note: we had no idea that there was a band called Autobody, we are intrigued).