I have a 2001 Prius with 88k miles, and expect 300k miles from it. Caveats are if somebody hits me, or if fuel costs more than double. Then I'll start reading the lithium battery threads!

I expect the Prius itself to be as reliable and low-maintenance as the best gasoline-only vehicles available. Some evidence has been already presented in this thread. Another is the exceptionally low wear that shows up in engine oil analyses. This is one tight little machine.

No doubt some parts will wear out, but amortized over 300k miles, their contribution to total operating costs will be low. Bob Wilson and a few others are leading the way in determining what additional care the unique transmission may need in order to run forever. There appear to be few if any other open questions on Prius longevity.

Crashes are removing Prius from the fleet far faster than any mechanical failures (that's where the ebay batteries come from). So drive carefully everybody!

DAS