CLEVELAND -- With the average car repair now close to $500, purchasing an extended warranty for your car would seem to make sense.

But many warranties aren't what they seem, and it's important to do your research before getting one, reported NewsChannel5's John Matarese.

Car salesmen almost always offer an extended warranty, or service contract.

But some warranties turn out to be very hard to use.

Christy Sullivan bought an extended warranty with her car for $1,400, which was supposed to have a $50 deductible.

But she learned the contract will pay only what the warranty company thinks a repair should cost -- in one case, one hour of labor for a three-hour job.

"They don't stick with any agreement, and that's the sad thing," said Sullivan. "You have this contract that says they're going to fix it and they always want to stick you with more."

The Better Business Bureau suggests finding out what an extended warranty covers before you buy.

Some don't cover overheating, engine gaskets, or moving parts, like ball joints.

The BBB says a good warranty covers most breakdowns, lets you go anywhere for a repair, and requires you to pay only a small deductible.

Manufacturers warranties typically cover the most, but they're expensive.

If you're considering a third-party warranty, ask questions, then check out the company with the Better Business Bureau for complaints.