 My Prius just turned 100,000 miles.  With little over four years of ownership, the only thing I had to do periodically was change the oil and replace a few air filters.  All mechanical systems have held up - I still have the original brake pads, muffler, and everything else.  My Prius has been extremely cheap to keep and I highly recommend it as a primary family car. As far as tires go, I'm still on the second set!!