As far as I could determine the CDW wasn't covered by any credit card and North American personal auto insurance won't cover you in Europe. We took the CDW for 10 Euro per day to be safe.

Diners Club also told me that they only cover up to a C class Mercedes event though I wanted an E class Stuck with the C class because it was covered.

I would call your CC and personal auto insurance companies to make sure what they cover and don't cover.

I think it was the CDW but it might have been LDW - sorry I don't remember which one it is.