I wouldent bother get another email address.
There is not much they can do with that.
Even if they try and reset your password.
Make sure your secret question is secure and there is nothing they can do with just an email address.
Its easy getting peoples email address, they dont need to go to auto trader to find it.
I can only image the scam goes something like:
1.) They pay by PayPal to you
2.) They send somebody to collect the car
3.) They claim they never recieved the car
4.) Open case with PayPal for refund
5.) They have the money & your car.
Still not entirely sure that would work...
Getting into your email address and seeing if you have paypal cant be the scam.
Even if they got into your account and made bogus transactions, I am sure you could get this fixed through PayPal.