What caused the car to stop at 80ks an hour could it be carbon build up.

Here is my opinion and mine alone, could be wrong, if you get another ride get another make!! Worked on a bunch of these over the years. Personally I think they have gone down hill. Dealer (Subaru) gave you a poor excuse I think. Oh, that gear (pulley) is a composit material, not entirely metal. Head gasket leaks are a problem as well, later on. They are just not consistent. Sorry but that is just the way I feel about this make! As stated may be entirely wrong, hope I am!