If you've been car shopping, new or used, you've likely seen "power-train warranty" in the paperwork.

The warranties usually cover parts that make the vehicle move, like the motor itself.

They typically come with new cars for a period of years, and more used car dealers are offering them at no additional charge.

They're even offering lifetime warranties.

Should you choose one pre-owned vehicle over another because of that warranty?

I'm not a big believer in costly, extended warranties.

And even with these freebies, I have a lot of questions.

Can you get service and repairs at other shops or only at a specific dealer?

Is it transferable if you sell the car? Most are not.

How much is the deductible per claim? Usually $100, but some jump after a few years.

And what does a power-train warranty really cover?

It usually does not cover brakes, wheel bearings, and other things that could be a problem.

Also, with most of these, you must get permission before work is done or it can void the warranty.