What's wrong with paypal?
There's a big no no on scamming people with trying to buy a car and sending money else where.
Even Craig's List and Amazon says, to avoid scammers, deal local, hand to hand transaction.
Also, if I am buying a car in the local area, if any service is used besides seller/buyer, then services have to use some type of state tax or internet tax due to item being sold within the same state.
EDIT: Also, never give out personal information. IF someone already has your email address and other personal information, they might be able to try to force some type of transfer. Not really sure if it's possible but if I am not physically looking at the car ready to buy on the spot, then I am not interested.