Summer vacation plans include renting a car or wheelchair van?

If so, your insurance agent, not your travel agent, needs to be first on the call list. And it's not too soon to start thinking about which credit card you want to use to pick up the tab. That's because insurance firms, car rental agencies and credit card companies are all competing for your insurance dollar -- and what they offer today could be very different from what they will offer next week.

Ultimately, it's up to you to make sure you're covered. So plan ahead. If you have auto insurance, call your agent and find out what kind of coverage you have. Most auto policies extend to rental cars. Ask specifically about two things: Collision damage waiver and liability.

Collision damage waiver, or CDW, covers any damage to the car you are driving. Liability covers damage you do to someone else.

"These are the two areas where you don't want to make a mistake," says Jeanne Salvatore, the vice president of consumer affairs for the Insurance Information Institute, a nonprofit industry sponsored organization. "These are the two areas that are costly."

In addition, if you're worried about theft of your belongings,

Check Your Coverage:

check your homeowners or contents insurance to make sure that what you're packing is protected. Ask your insurance agent if there is a limit on your collision insurance. If you normally drive a 10-year-old van, but are planning to rent a brand new Chevy Venture which has been modified and costs in the neighborhood of $45,000, make sure that your policy will cover the complete cost of replacing the more expensive vehicle.

Some companies don't limit the collision insurance -- meaning you are fully covered no matter what you drive. Other policies set a limit or exclude certain vehicles, like luxury cars. Find out ahead of time what the rules are. If you normally drive an old clunker and you've dropped your collision insurance -- or you don't have either a car or insurance -- Small companies like wheelchair van rental companies don’t normally offer CDW or LDW coverage.

You’re best bet is to use a credit card that will give you coverage. If you rent cars frequently, get estimates from your regular insurance agent on a policy to cover you -- it might be the cheaper alternative. .

Some credit card companies will supplement your auto insurance when you rent a car. Diners Club, for example, provides unlimited collision insurance for a limited period. But the policy excludes exotic cars -- like Porsches and Lamborghini's, so you’ll need to make sure they will cover a wheelchair accessible van and it’s modification-- and it does not include liability coverage.

Also, if you are able to purchase additional collision insurance from the rental car company, you automatically invalidate your Diners Club coverage.

Shop carefully. Two people can carry the same credit card, issued from the same bank, but still be eligible for different rental benefits.

In the case of American Express, even having the same level of card -- regular, blue, gold or Optima Platinum -- is no guarantee you have the same insurance privileges. Call your credit card company and get the results in writing -- they can fax you the information if you're in a hurry. If you're not, call them twice. It's not unheard of to get two different answers to the same question from the same company.

"There's an 800-number on the back of the credit card. Call and ask specifically how much coverage do you have and for what. When you talk to your credit card representative, ask about collision and liability. Then find out if there are any exclusions. Besides excluding certain types of cars, some companies will refuse to cover you if you're traveling from another country and driving in the U.S. Others will cover you, but only for a limited time.