I've found that the trick is to dispute the charge. I've had the occasional chipped windshield and Hertz then adds about $150 to the rental as a damages fee. when you open an insurance claim Hertz never responds with the requested info. so, AmEx insurance tells you - no response from Hertz so we're closing the case. But, if you dispute the charge with AmEx, then Hertz will respond to AmEx to prove the validity of the charge. Then AmEx will send that proof to you (usually, proof of a repair). If you then send that to the AmEx insurance folks they will pay AmEx for the charge. Is that stupidly complicated and repetitive - yes. But I haven't found a better way to make the AmEx system work.