There were two occasions where I had rental car damage and AmEx, which was primary (I don't own a car and hence have no insurance) refused to cover loss of use, administrative fees, and, in one case, a towing fee (although they said they would pay the towing fee if Avis submitted proof, which it did not). IIRC, in the second case, the uncovered charges amounted to over $500. I lawyered this myself, and never paid it, but, following some advice on another Internet board, switched to using MC for car rentals; I had called my card issuer and confirmed with them that loss of use WAS covered. This thread is leading me to conclude I had better have another call.