Who Dented the Turtle?

The Turtle is a horrible driver. She drives like a maniac. One morning, her brakes fail and she winds up in Skunk's garden. The brakes seem to have been sabotaged! It's a crime, but who is responsible? Sherlock has an accident with Hermione's car. He has the car fixed, but fails to tell her about it. He gets the car back and it's been totally customized. Good thing Hermione likes it that way.