CLEVELAND -- Many vacationers are opting to drive instead of fly this summer.

But there are some things you should know before you rent a vehicle. In this week's Betcha Didn't Know, On Your Side Troubleshooter Chris Caswell reported that there are ways to cut corners and save money.

Whether you lease a car, you're afraid of flying, or you want to control the trip, renting a car is quickly becoming the way to travel.

"We're renting a car because it was actually cheaper than ground transportation, and we needed it for the last day that we're there," customer Lauren McMahon said.

But before you load your luggage, there are some things that your car rental company won't tell you.

First, make sure the car is in good driving condition. It may take a little bit of time, but it's worth it, because you don't want to be blamed for damage you didn't cause.

"If you see anything, then you need to report it to the car rental place before you pull out of the parking lot," said Luba Horsky of AAA.

Also, rental agencies at the airport charge the highest rates. It's best to wait until you get to your hotel to rent a car.

And you may be offered a tempting deal: You are approved for a mid-sized car, but you could upgrade a luxury car instead. But experts said to look before you leap.

"Your auto insurance may only cover you up to $50,000, and if something happens to this Jaguar and it's $70,000 or $80,000, then you'll be liable for the difference," Horsky said.

Another trap is pre-paid gas. It's convenient, but you pay extra for it.

"So, you're going to be taxed with all these extra surcharges on top of that fee, so you are paying a double tax on that fuel," Horsky said.

You may be charged for the full tank, even if you don't use it.

It's best to call ahead of time and ask for all of the charges up front. Ask for the bottom-line price, and you can even ask them to fax or mail the proposal.