Of course, Dobel didn't exist...
He was Jerry's hidden "assertive" side. Always there when he needed to be brave or tough. The red car is a classic Freudian construct, possibly representing Jerry's penis or maybe even his mother's womb. Dobel wreaks havoc in Jerry's comfortable, non-confronational life, forcing him to make the tough decisions that change his life.
(I'm busking, of course, but it's a neat theory, no?)
Awight we're The Daamned we're a punk baand and this is called Carn't Be Appy T'day!