A local News station regularly does stories on people who have bought extended warranties for their car. Then they have a mechanical issue, and the issuer of the warranty finds ways to weasel out of covering the repair. The consumer advocate journalist might once in a while get the warranty issuer to honor said warranty.
Personally, I'd take the money you'd spend on an extended warranty, and invest it in something that will accrue interest. Then IF you ever need a repair, you'll have the money for it.