I think it would be a good idea if they chose one interior from an existing premium car, say the Volkswagen Golf GTI '01, or any other premium car with an interior that would look fit in many other cars, and use that interior for most or all of the standards. Then, for the more unusual standards or the supercars, they could use an interior from a premium supercar, like the Acura NSX. Just a thought.
EDIT : It would also be neat if you could hang fuzzy dice from your mirror or hang an air freshener up there, or put a hula figurine on the dashboard, or get a silly looking cover for your steering wheel. It would do wonders for car customization.
All they need is a laser scanner to generate the polygons on the cars in my opinion.