I don't think Amex will fight it for me because I had to have "rejected" the damage waiver coverage offered by the rental company. I could not reject that specific coverage because the car rental company only offered a "package" deal, all or nothing. I didn't dare go without coverage for personal injury mainly. This is going to be a difficult battle from what I can tell. We drove on the local roads without incident, but once we hit the highway and started going above 50 mph or so, the noise and difficulty getting uphill started. I don't know if there was black smoke from the exhaust. I wasn't the one driving, so I never looked back. If my husband noticed it, he didn't say anything.