Oh, it's got to be a Mini, I was so happy when Rory had one in TEH. They are cheap and cute and easy to fix, but then they break all the time, but the Doctor wouldn't mind that and would keep one going long past where it was convenient. I think that bit all stands as it is, actually, because of not being too specific. I got that River had crossed to the driver's seat, yes, and she could probably do that but only because she's smaller than who had been driving. It involves climbing over the handbrake. The steering wheels tended to be big, too, and awkward for long-legged people to get their knees round, so the Doctor would have a lot more trouble turfing her out than she has.

Both front seats are little fixed-back bucket seats and they tip up on hinges at the front to let people in the back, and they can get in either side.