[Sherlock]

>So now the cops have questioned him, and he's off the hook "for the moment" so he's going to take a vehicle that he knows is directly linked to a kidnapping/murder back to his REGULAR mechanic, leave it out in the open, windows down? C'mon, Ricci may not captain the good ship Brainiac, but he's not going to make such a blatant mistake.

First of all, he had to bury the evidence at all costs. He had to take care of business and didn't have a little time. My guess is he felt he had to get the Jeep back in Moul's shop before it closed and he just didn't have time to do the cleanup. Also he had to get home and get cleaned up before the police came by asking questions. Also a possible post-homicidal depression could contribute to sloppiness. I can't explain why he did what he did, but the things we do observe tell the story of what he did.