Well, I don't know, now, but it seems obvious to me:

He took care of the outside (obliterating the old sheriff's logo) with a quick 'n' easy coat of primer. Then he moved on to the more time-consuming part, inside the engine compartment ("he looked inside"), rebuilding the engine and souping it up so it'd go well enough to outrun the revenooers when necessary.

That's what it says to me, anyhow ...

JtT