there are occasional cases when warranties and guarantees make sense to purchase (and yes, you always purchase them- sometimes its just built into the cost of the item). when you buy a $5-600 laptop from best buy and they offer you a year of accidental damage for under a hundred bucks, okay, maybe it's an okay move (worst case after 11 months you smash it with a hammer and get a new one). this is just generally so not the case with cars, though. i can often recommend extended automotive warranties so long as a) it's a good warranty that is as close to factory bumper to bumper coverage as is possible and b) it's reasonably priced. but long limited coverage one-owner powertrain warranties? no thanks. 'i hate this car' insurance? no thanks.