I bought one extended warranty. Blew a head gasket. It wasn't an "internally lubricated part" so warranty paid zip! That was a real bite!!
IMNSHO, new car warranties are like Health Insurance. Doctors, sorry I mean Dealers, will to everything under the sun, send outrageous bills to the insurance company, and you'll be happy because YOU aren't paying. Never mind if there is a less-expensive procedure, there's no incentive to spend the time looking because it's "free" money and the patient, I mean customer won't object.
I no longer buy warranties. I'll put the money into an interest-bearing account and keep up the required maintenance. Then, I can pay for a normal level of repairs. If I need too many repairs I'll jettison the troublesome beast and buy something that doesn't break as often. Yes, sometimes I've come up the "loser" on such a deal, but not by much.
My wife says I'm cynical. I'm an engineer, so I tell her I get paid to be cynical. If I didn't I'd still be cynical because it's fun.
She insisted that we add electrical coverage to the StarMark on her 96 E300D, so I don't _always_ do as I rant...