Before the hard sell on rental car insurance, check your own auto policy

Before visiting a rental car counter this summer, it's wise to make two telephone calls: one to the insurer that covers your personal car and one to your credit card company.

Many people feel pressured to buy the rental company's insurance coverage on the rationale of better safe than sorry, even though it can cost up to $30 a day, said Norma Garcia, a lawyer with Consumers Union, the advocacy and policy arm of Consumer Reports. But if you verify coverage you may already have before setting out on vacation, she said, "You can be safe and not sorry."

Many, but not all, credit cards offer rental coverage at no extra cost, as a perk for customers when they pay for the rental with the card and decline the rental company's offering. Coverage varies, however, and depends not only on the card's payment network — like Visa or MasterCard — but also on the issuing bank, according to a recent analysis from CardHub.com, a card comparison website.

To avoid surprises, contact your card company to confirm that your card indeed offers insurance protection, and ask about any limits or exclusions. Ask for the terms in writing.

Most card policies cover rentals of up to 30 days, but others limit coverage to two weeks. Some exclude some SUVs, trucks and expensive cars.

Many cards also exclude coverage in certain countries (Ireland, Israel and Jamaica are often left out, as is Australia.) Citibank and Discover credit cards may come in handy when traveling internationally, according to the analysis, as they cover cars globally.

The analysis evaluated 10 large card issuers on 11 criteria, including the duration of coverage, exclusions and the card's claims process. Citi cards generally offered the most favorable insurance coverage overall, the analysis found, although Citi's claims process may require a bit more paperwork.

Keep in mind that credit card rental car insurance is usually secondary, or backup, coverage that pays for expenses, like your deductible, that your personal auto policy may not cover. And the card policies generally don't provide liability coverage, for damage to other cars or injuries to other people. Check your personal auto policy.

If you own a car, your auto insurance often covers a rental car at similar terms.

If you have dropped optional coverage on your car, like collision coverage, to save on premium costs, however, your rental car may not be covered if it's damaged. In that case, you should consider buying the rental company's "loss damage waiver," also called a collision damage waiver, so you won't be responsible for damage to the rental car, said Loretta Worters, a spokeswoman for the Insurance Information Institute.

Rules vary by state; confirm the details with your insurer.

In most states, personal auto policies don't cover something called "diminished value," or a drop in the car's value because of damages and repairs. Some insurers may add this option with a special "endorsement" on your policy.