Congratulations on rolling over 100k miles. My '05 just rolled passed 36k miles, and shortly before I did I decided, after much debating, to purchase the $990 Toyota Platinum extended warranty sold through Toyota of Greenfield MA. I have had zero problems with my Prius, and I'm not ordinarily an extended warranty guy, but since there's so much complicated electronic stuff in the Prius, and since it basically can only be serviced by the dealer, I felt more comfortable having the warranty in place.Perhaps not entirely rational, but whatever it takes to sleep better at night.

Regarding the batteries - this from priuschat.com:

If you live in California, Maine, Massachusetts, New York, or Vermont, the hybrid battery pack is covered separately under the added California emissions warranty. The Hybrid Battery Warranty in these states is 120 months (10 years) / 150,000 miles. That's according to the "2004 Toyota Prius Owner's Warranty Information" booklet, PN 00505-T2004-PRIUS, page 6.

The batteries in all hybrids are designed to last for "the life of the car". Some early manul-transmission Insight owners have had problems, but Honda has extended the warranty to cover those people -- on the honda_insight Yahoo group, some guys with more than 100K have had their packs replaced free of charge from Honda, while others of us enjoy the fact that *if* we have the problem in the future, we're covered.

As for why your fuel economy may be decreasing, there are a few things to check right away: 1) that your tire pressure isn't below Toyota's specs; 2) that your oil isn't overfilled; 3) that you're not out of alignment; 4) that you're not carrying a few hundred pounds of extra weight. Other things that can negatively affect your fuel efficiency: 1) using the air conditioner; 2) using a 10% ethanol blend (if you're not accustomed to using *any* blend); 3) using E85 (which no Prius on the road is built to do -- stop immediately!); 4) short trips (less than 10 minutes in length); 5) strong winds; 6) road construction (sudden stops, bumper to bumper stop-n-go traffic, rough road surface); 7) idling the engine.

peace,
Linda
www.hybridfest.com

E85 is 85% ethanol. Not many cars are set up to run on it.

I agree with Geo - I suspect that we will eventually find out that Prius engine on average will last much longer than convention gas engines. Not only for the reason you state, but also because it can never be lugged or over-revved since it's all under computer control.

What's not known is the longevity of the inverter since it generates craploads of heat, and heat is bad. Do any of the components get heat fatigued over time? We shall see.