This has been discussed in many threads. But I will give you example of why most dealers are hesitate beside the card merchant fee that can be high as 3.5%.
If you buy a Rolex and you dispute the charge the Jeweler can take you to court and the judge will make you return of the Rolex plus damages legal fees etc.

If you buy a car on any credit/charge card the car has a Title that can be conveyed to someone else. You could sell the car dispute the charge and the dealer would find it difficult to get a judge to order it returned to the dealer.

If you have excellent credit and are reputable with assets you can purchase an entire vehicle at most small car dealers on a credit or charge card. So you can forget Penske.