CHARLOTTE, N.C. -- With Charlotte's economy crunch getting worse, used car sales are way up.

More people are bypassing new cars and saving money by purchasing pre-owned vehicles.

But with the savings comes a risk. You could end up with a car that's been wrecked, flooded or salvaged and not even know it.

Channel 9's Don Griffin explains how to protect yourself.

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Eyewitness News brought three used cars, all for sale right now in Charlotte, to the station.

But one is not like the others – it’s been wrecked and then repaired. Two Channel 9 employees were put to the test to see if they could figure out which one.

Rossana looked them over first, but admitted she really doesn't know much about car shopping. So she got a hint.

“The car was sitting when it was hit,” Griffin said.

After a little more study, Rossana decided the Volkswagen in the middle was the one that's been wrecked.

Then Kevin got a turn. He checked out the Buick and also the Chevy Impala.

But he too was suspicious about the VW.

"The way it sounds when I crank it up, it just doesn't sound like the other two cars. The other two cars sound smoother," Kevin said.

"So you're saying this Volkswagen is the one that's been wrecked? You're sure about it?," Griffin asked.

"That's my final answer," Kevin said.

Chris Basso with CARFAX, the company that does history checks on used cars, had the answer. He said a lot of cars that look clean are not.

“We've seen cars that have odometer fraud, airbag damage, they have frame damage. There are a lot of hidden problems,” he said.

In fact, CARFAX reports the number of salvaged cars, those wrecked and re-built for sale, jumped 65 percent in the Charlotte area over the last 5 years, meaning buyer beware.

Our two buyers were in agreement. They picked the Volkswagen Passat as the one that was wrecked.

"Unfortunately, like most car buyers, (they’re) wrong," Basso said. “It is the Impala that was wrecked. The Impala sustained a rear-end collision, received enough damage to require a police report, and was fixed up to make it look like all of these vehicles."

“Very surprising, very surprising. I wouldn't have picked this one. It was actually between those two," Rossana said.

The CARFAX report for the Impala shows the accident happened in July of 2006 in Virginia Beach and the rear was damaged. But without that report, the only tell-tale sign is a color difference so slight it's hard to detect.

“This rear bumper and quarter panel has been replaced. The color is just a little off from the original paint job,” Basso said.

Basso advises having a mechanic check out any used car before you buy it. It'll cost about $100 but could prove priceless down the road.

Rossana said she's learned another lesson.

“Run the vehicle report and make sure it's not been in an accident,” she said.

“And not just rely on your feelings about the car?” Griffin asked.

“No, clearly that would be a mistake!” she exclaimed.

Most dealers will provide the CARFAX report to you for free if you just ask. If not, you can buy it online for about $30.

Even if a car was in an accident, if it was repaired well then it might be fine. But, you need to know ahead of time. You might be able to use the information to negotiate a better deal.

VIDEO GUIDE: Tell-Tale Signs A Used Car Has Been Wrecked

LINK: Consumer Guide To Buying A Used Car

LINK: To Obtain A CARFAX Report From CARFAX.com