I would suggest:
He backed [the car] into the garage instead of pulling in head-first
You can also be more succint:
He backed in
and shut the car off (entrou de ré)
He pulled in [head first]
and shut the car off (entrou de frente)
Note: "to pull in" is usually already assumed to mean "head first".
Mais como digo somente:
"Entre de frente".
Pull in head first
Drive in head first
"Front first" also works in this context.