The best thing to do is to call your insurance agent and credit card company in advance. Just because you’ve used a gold or platinum card in the past, don’t assume that it still offers the same protection plans — the cards’ insurance benefits can change.

“More often, these prestigious cards are starting to change the advantages they offer to their cardholders, and often times the cardholders are unaware,” said Carolyn Gorman, vice president of the Insurance Information Institute in New York. “You could be driving uninsured and not even know it, until you get into a bad accident and have no insurance to cover you. It’s a dangerous, scary thing.”

If you’re not insured through a policy or credit card, the long list of available options can seem intimidating, with dozens of plans that can add as much as an additional $40 a day.

“This is just a classic way for these companies to make more money,” said Greg Daugherty, an executive editor at Consumer Reports magazine. “This is usually money that people are spending unnecessarily.”

Car rental agreements vary from company to company, but these are a few plans most state laws require them to offer:

The collision damage waiver, also known as optional vehicle protection or loss damage waiver, can cost as much as $19 per day. This is not technically an insurance product, but instead shifts liability for collision damage from the person renting the car to the car rental company. This also covers for “loss of use,” or time a damaged car can’t be rented because it is being repaired. Waivers, however, can become void if the accident was caused by driving illegally or on unpaved roads.
Liability insurance, which provides protection for up to $1 million, costs between $7 and $14 a day. A driver would already have this coverage under their own car insurance.
Personal accident insurance covers medical and ambulance bills for the driver and passengers in the event of an accident. Opting for this would cost an additional $1 to $5 daily, but health insurance or personal injury protection under auto insurance would already pay for those types of bills.
Personal effects coverage is not always included in regular insurance plans. This protects against theft of items in the vehicle, such as laptops, golf clubs or cash. The coverage generally costs between $1 and $4 a day. It may be more cost effective, however, to purchase a floating policy under home or renters insurance, so that valuable items are fully protected at home as well as on vacation.

If money isn’t a huge issue, it almost seems to me it would be better to buy the additional insurance, for the reasons you cited. But I don’t have intricate knowledge of the subject.