Hi Took my 2004 Prius for it's yearly service at the Toyota garage recently. I was talking to the Service Advisor and he mentioned two Prius that had come in for repair over the past 4 months. One (a 2004 car) had 322,000 miles and the other (a 2005 car) had 346,000miles. Both had a full Toyota service history - even if the service books had run out of pages to apply the service stamp! Both petrol engines were worn out. (Burning oil, poor compression etc.) Both had collapsed drivers seats. But on both cars the traction battery and the electric motors were fine. It was the petrol engine that expired, not the hybrid system.