 Our Prius drove fairly well for the first 100K+ miles. Then trouble started.  Recently, the warning triangle came on, and as instructed in the manual, we took it to the dealer repair shop. They didn't know what to do based on the computer scan and Toyota HQ told them to clear the codes and test drive it. They did, but a few miles later on the way home, the warning came on again! I quickly returned to the shop.  Then I was told the part I needed would be $4K+ with many hrs of labor. I said no and am driving the car with the warning still on. They'd only give me $2K trade in, so we kept it and bought a Chevy Cobalt.  Had I to do it again, I'd sell it at 100K miles!