By Amy E. Feldman

PHILADELPHIA (CBS) – If you’re offered insurance on a rental car, should you take it?

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A man in Switzerland got a coupon deal to rent a Ferrari for the equivalent of $40. Turns out, not a great deal for a guy not used to driving a Ferrari. The inevitable crash caused $400,000 in damage, and now his insurance refuses to pay the tab.

If you’re renting a car and you’re asked if you want extra insurance, should you get it? The answer is for you to ask questions, often before you go to the rental agency.

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The first thing you need to know is whether your current auto insurance covers you in rental cars, and if so, what is excluded if you’re driving one. Some credit card companies cover rental car insurance, but you need to call to ask what deals they have with which agencies. And then, of course, use that credit card to rent the car.

Rental car companies offer what you think is insurance but is actually a Collision Damage Waiver (CDW), a guaranty that the rental agency will pay for all damage to the rental vehicle, but not personal injury or damage to your personal property.

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So you can pay for CDW for the comfort and convenience of knowing you won’t be charged for scratches on the car if you choose, but really be sure to understand ahead of time what’s covered, what isn’t, and whether you’re really more of a Focus rather than Ferrari type of guy.