Putting on my former bank internal auditor hat: If the credit card plan has a security interest in the vehicle, why would they need to charge such a high rate? Other lenders would offer conventional new vehicle financing at a far lower rate, making the card very uncompetitive. This would reflect negatively on EM. As an example, Kim Kardashian had a credit card marketed in her name. The rate and fees were so high that it was soon taken off the market due to her followers' anger.
Home equity lines of credit permit you to use a credit card, too, but the collateral keeps the rate low.
I would say we just don't have enough information to really know what the credit card deal will look like.
If this is a secured credit card with a very low usable limit intended solely for buying gas then the interest rates are likely to be quite low.
However if this is a normal unsecured credit card carrying a large balance then anything is possible. This does not necessarily mean the rate will be high as there are all kinds of cards with low introductory balance offers however these usually have very high penalty rates as well if the program is not followed.