I found a 2012 on my local Marketplace, a good price for a well-optioned Prius with almost 200k miles. Just one fly in the ointment - it's throwing a check engine light for a P0301. Okay, sounds like it needs a head gasket, maybe they should take a couple thousand off the price, lol? Not so fast. The owner told me that he had head gasket issues about 20,000 miles ago, and his mechanic replaced the head and camshafts with an aftermarket one (???) Not sure if that's rebuilt or whatever. Seemed a little odd to me; I would think you could use the old head, maybe mill it flat and put in some new valve guides. Sounds like the operation was a success and the car is now driving nicely. Anyway, the car has fairly recently begun throwing a P0301 (cyl 1 misfire). The owner has tried replacing plugs and coils, but the misfire remains. Owner says that it's not using any coolant. Seemed to imply that it wasn't even running rough, if I remember right. He said a compression check showed everything good. As far as I can tell, there are two possibilities: 1) the head gasket fix has failed again, due to a defect in materials or workmanship. Or 2) there is some other cause for the misfire. The only thing I can really guess is a fuel injector. Of the two possibilities, #1 seems WAY more likely to me, and I should probably avoid this car unless it is deeply discounted. What do you think?