I have a 2001 Prius with about 122,000 miles on it. I was told by the dealership today that the hybrid battery needs to be replaced and it will cost $3,700. Here's my story. About 2 months ago I did not drive the car for about 4 days. When I cranked it up, the turtle light came on and I could tell the car wasn't accelerating right. After reading the manual, it seemed like the hybrid battery was low on power and after driving for a while, everything seemed fine. This happened a couple of times that day, so I took it into the dealership to have them check into it. Unfortunately the dealership totally mis-diagnosed the problem because no error codes were thrown by the turtle light problem. I didn't let them do any repairs, and the problem seemed to go away. Occasionally when I'd first start up the car, I could tell the hybrid engine seemed a little weak, but the problem went away after a few minutes of driving. Fast forward 2 months. Last week, I was driving and the master hybrid warning came on. I was far from home and the car felt like it was driving ok, so I drove on home. It was Thanksgiving week and life was busy, so I drove around with the warning light for few days. On Friday night the Prius decided to revolt. I was driving on the highway when suddenly the car downshifted to a low gear and the parking break light came on. I couldn't get it out of the low gear, nor could I get the parking break light to go off even after pushing and releasing the break, so I pulled off the road and shut off the car. When I re-started, the parking break light went off and the car was driving fine again. This same problem happened three times that night, but I managed to make it home. The next day I drove it up to the dealership. I ended up stuck in traffic and the car started acting really funny. The gas engine would shut off like it normally would when the car is stopped. Then after 2 seconds, it would crank up the gas engine and begin charging the battery. After 2 seconds of charging, the gas engine would shut off again. As I watched the battery charge on the screen that shows the car's energy flow, I could see the charge fluctuating wildly. This repeated itself as I freaked out in traffic, but fortunately when I'd start going again, the car would drive pretty much normally. So, today the dealership tells me that the hybrid battery needs replacing. I just thought I'd share my story. I love my Prius. Besides needing a new catalytic converter, which seems to be a common problem, it has been very reliable so far. I talked to the sales guys tonight to compare fixing vs. buying a new one. They're not going to give me a whole lot for a trade-in, so it looks like I'm going to replace the battery. Hopefully we won't see any other major repair for a while. *edit* Sorry. I think I posted this in the wrong area.