Hybrids like the Toyota Prius may save money on fuel, but car shoppers have long wondered how those batteries hold up over the long run. In fact, we’re often asked, “When do the batteries need to be replaced, and how much will they cost?” These questions are even more important now that the Prius has been on the market for 10 years--there are many used models on the market. But is it risky to buy a used hybrid?

Early adopters of the hybrids took a risk with the new technology. The lifetime of the batteries and the cost to replace them wasn’t clear. After all, when it comes to standard car batteries, most don’t last more than a few years. And anyone who has a laptop that is a few years old is most likely aware how significantly battery life can degrade with age.

Based on data from over 36,000 Toyota Prius hybrids in our annual survey, we find that the Prius has outstanding reliability and low ownership costs. But we wanted to know if the effectiveness of the battery degraded over the long run. So we hooked up a 2002 Toyota Prius with nearly 208,000 miles on the clock to our testing instruments and compared the results to the nearly identical 2001 Prius we tested 10 years ago.

Conclusion: We found very little difference in performance when we tested fuel economy and acceleration.

2001 Prius 2002 Prius Fuel Economy 2,000 miles 206,000 miles Overall 40.6 40.4 Highway 48.6 46.3 City 30.5 32.1 Trip 48.5 46.3 Acceleration 2,000 miles 206,000 miles 0-30 mph (sec.) 4.3 4.4 0-60 mph 12.7 13.1 1/4 mile 19.3 19.4 1/4 mile mph 74.6 73.6 45-65 mph passing 7.0 7.3

Our testers were also amazed how much the car drove like the new one we tested 10 years ago. It certainly didn’t seem like a car that had traveled nearly the distance to the Moon. We were also surprised to learn that the engine, transmission, and even shocks were all original.

If the battery ever did need to be replaced, it would run between $2,200 and $2,600 from a Toyota dealer, but it’s doubtful that anyone would purchase a new battery for such an old car. Most will probably choose to buy a low-mileage unit from a salvage yard, just as they would with an engine or transmission. We found many units available for around $500.

So is an old Prius a still a good value? We think so.

—Jake Fisher

Has your car made it to 200,000 miles or more? Join the discussion in the “200,000-Mile Club” forum. Also, see our report Make your car last 200,000 miles.

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