You have to remember that the engine does not run as much as a regular automobile, as it stops every time you do, as well as when there is no load on it. The engine is an Atkinson Cycle engine, which means it has no torque at the low speed, and lots of it at the higher RPMs, where it runs at its most efficient. The big batteries make up for the lack of low end torque, giving you an amazing boost upon acceleration.

But, I expect what you are really asking is whether the batteries are reliable. Well, my brother is a Toyota Master Diagnostic Technician for a Toyota dealer in eastern North Carolina, a member of SE Toyota (five states). He asked his SE Toyota representative if an owner has EVER paid for a Toyota traction battery in the five states of SE Toyota, and the answer was no. I repeat, no owner has EVER have to pay for a traction battery failure, since they went on sale in 2000.

I have owned a 2002 Prius, which I sold with 78,000 trouble-free miles. I currently own a 2004 Prius with 62,000 trouble-free miles and a Camry Hybrid with 25,000 trouble-free miles. None of my hybrids have EVER been in the shop except for scheduled maintenance, like oil and filter changes. There are no drive belts, no starters (the battery does it), and the A/C is electric, like your home, rather than belt-driven. Even better, the CVT (transmission) only has about 80 parts, rather than the 800+ parts of a conventional automatic transmission. Spark plug changes are scheduled 100,000 miles apart.

Overall, they have been the most reliable cars that I have ever owned, and I have owned quite a few, starting way back in 1970.

I hope that this answers your question, and that you have a great day! Also, I would love to know if any of the others that answered this question actually OWNED a hybrid. I seriously doubt it, from the tenor of their answers. I am giving you tried and true FACTS, not bombastic hyperbole.

If you take a look at some of the reviews for 2001-2003 models, you’ll find people who have driven their Priuses well over 100,000 miles–and their detailed comments about reliability.

That’s probably the best place to get a good amount of information. (Links below, starting with 2001 model year and going up.)

But if I had to speculate, I would say that they are reliable because they don’t have much horsepower. That means drivers can’t put a lot of stress on the powertrain because the acceleration isn’t strong enough to cause any damage. Drivers won’t try to tow anything. Drivers won’t beat up their car from spirited driving.