Wirelessly posted (BlackBerry7130e/4.1.0 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/104)

As of a couple of years ago, some credit card companies were representing that they would cover Priceline rentals. If anyone is interested in exploring this, I would recommend asking the credit card company for a letter or Email, as opposed to an oral, response.

As far as charging the entire rental to a credit card, MasterCard specifically allows one to take advantage of a rental company discount or promotion (coupon) as long as at least one full day of the rental is charged to the card.

I doubt that a credit card company would exclude coverage based on a reservation that did not include a credit card. Both Visa and MasterCard talk about initiating a rental "transaction" or "agreement/contract." I don't think that a reservation counts, especially since one can sometimes rent a car by walking up to a rental counter without a reservation. (A prepaid/non-refundable reservation might be a different story.)