The thing that will give away the scam is if he offers to pay you a lot more money than you're asking and then tells you that you can keep some extra as long as you send him the balance in a cashiers check or some other type of secured funds. Basically they write you a bogus stolen check, your bank cashes it for you since they don't know it's bad, you send out the car and the balance of the money based on the funds you thought were legit and you get left holding the bag.
However this is the first I've heard of it coming from Scotland. Mostly it's out of South Africa and such.
Rick