<<mentions the above in conjunction with "rental">>

When you rent a car you either purchase a "collision damage waiver" or accept responsibility for damage caused to or by the car. If you decline to purchase the waiver it is typically because your own automobile insurance policy will also cover a temporary replacement vehicle. Many credit cards offer some type of car rental insurance benefit, but most specify that they offer "secondary" coverage, which means you must file a claim with your insurance company and the card will reimburse only your net out-of-pocket expense. Diners provides "primary" coverage which means they (usually) will process the entire claim without involving or notifying your personal carrier.

dennis