There would be no problem, but unless you pay the full amount of your car payment to the CC every month you will end up spending much more for the car due to the CC fees and interest. In essence you would be paying interest on the initial car loan, then interest on the CC. If you are talking about tranfering the entire car loan to a CC, be sure its at 0%, because other wise you will be paying interest on interest again. All in all there is no real point to doing that, unless you just trying to reduce your open accounts, and consolidate you debt.
Shaftiel