Beachgirl,
The best thing to do is call the credit card company. They can give you Mastercard and Visa tel#'s. When you speak with MC/Visa request a "Guide to Benefits". The guide will provide you with the "extra" benefits you have with MC/Visa. There are several "levels" of Mastercard and Visa benefits that have different coverages (i.e. some have
travel insurance).
I just did this a few months ago and I received it in writing so that I had peace of mind during my car rental. In addition some car insurance policies carry coverage as well.
Hope this helps.
Matt