Limits on car payment with credit card
I have bought two new cars with credit card downpayments in the last four years. Got some miles on each. In both cases (two different dealers) I was told the max they would take on a credit card was $5,000 which is what I charged. There was no suggestion that I could pay so much one day and then pay more on a credit card the next. As mentioned earlier in this thread the dealer has to pay the card company an interchange fee and that can cut way into profits. They are apparently happy to take the card for a downpayment to try and lock you into a deal. After that, cash, check or financing is what the dealer wants.
By the way, its not clear to me that paying with a credit card should involve reporting to the government as a cash payment might. After all, credit cards have a clear paper trail. I don't think I have to report my Amex card to customs when I leave the county even if I could charge over ten grand on it in one day.