One problem related to manifold/header/muffler/tail pipe has been reported for the 2012 Toyota Prius. The most recently reported issues are listed below.
Approximately 2 months ago I started having problems when starting the car in the mornings or after the vehicle sat for a while. When starting the vehicle it would shake and run rough but would run good after it warmed up. I took it to my local Toyota dealer and a manifold and a sensor was ordered by the dealer. The next day I went back to the dealer to have the parts installed. I sat in the waiting area for over 2 hours only to be told it was not the manifold and sensor. After a scope was used to diagnose the problem. This time I was told I either had a leaking gasket or a cracked engine head. This Prius v only has 94245 miles on the engine. It has always had regular maintenance at the Toyota dealer. The dealership quoted me to replace the engine at $6000. 00. I have never had a vehicle with less than 100,000 miles usage to need a new rebuilt engine especially a Toyota product. I am very disappointed in Toyota. This was a known concern on Toyota's part and it was not properly addressed in a recall, now I am left holding a very expensive bag. How many other unsuspecting,customers will you lose besides me.