We rented a car for over 3 weeks this past summer when we visited Glacier National Park, Calgary, and Banff National Park. We were on our way back to Salt Lake City to return the car when we encountered a stretch of the interstate which had been chip and sealed. Needless to say, vehicles were throwing rocks all over the place and one found our windshield. When we returned the car, the agent suggested we contacted our credit card company and they would cover the damage. We had used our Marriott Visa card. When I called, they were very nice; however, I was told that the car was not covered because we had rented for more than 15 days. I guess I should have explored the rules more thoroughly, but I had not. We waited from July to October (hoping it had been forgotten about just kidding). When we were notified of the damage claim in early October, I contacted our insurance company. Nobody seemed to know what was covered on a rental car, but I thought we had finally gotten it straightened out; however, we were contacted by the agency yesterday and informed that the insurance had only paid part of the claim.
The moral of the story: Make sure you know the specifics of the coverage on a rental car when it is rented for more than 15 days.