I have moved your post into the established thread on this topic.

In this circumstance the CDW benefit of any credit card becomes primary, but you need to understand that this only covers damage to the rental car itself. It provides no insurance for damage to another car, other property, yourself, or another person. The owner of the car (the rental agency) will have some insurance to cover those aspects, but you should discuss with your homeowner's insurance agent whether the liability provision of your policy would cover you in the event of a serious accident.