Reader Question: Prius Maintenance Costs?

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Here’s the latest reader question, along with my reply! 

Harvey asks: I own a 2010 Prius with 66k miles. Where can I check Prius maintenance costs and record of failures as car ages? A friend recently blew a head gasket at over 100K; the cost to repair was $3,900.

My reply: Your Prius has very low miles for the year; I would not worry about a head gasket failure for that reason and also because the engine in your car is not prone to that problem.

My concern, if I owned a nearly ten-year-old hybrid (Prius or otherwise) would be the aging battery pack – and the cost of replacing it.

You may have already noticed a decrease in gas mileage, which is inevitable because over time, the battery in your car will be less and less able to hold a charge and your Prius will depend more and more on the gas engine for power.

The gas engine will also run more often – even when the car isn’t moving –  because it’s continuously trying to keep that weakened battery charged and because the battery is too weak to power accessories on its own.

It is analogous to having a weak starter battery in a non-hybrid car. Over time, it is less and less able to hold full charge; the alternator(which generates electricity to run the car’s electrical systems once the engine has started) tries to keep the battery “topped off” after each start – but eventually, the battery just hasn’t got enough gumption to start the car one day.

The difference is that in the example above, once the car is running, there isn’t much effect on fuel economy – and replacing the 12V starter battery is a matter of $100 or so and easily do-it-yourself.

In a hybrid, the cost of battery replacement can easily be as much as your friend paid to get the head gasket job done – several thousand dollars.

The good news is you don’t necessarily have to replace the battery in order to continue driving the car. But your mileage will be much lower, due to the fact that the car will increasingly rely on the running gas engine to keep you moving – and to power the vehicle’s accessories.

Because of the very high (and inevitable) cost of replacing a hybrid vehicle’s battery pack, I recommend leasing these cars or trading them in well before they reach the age (or mileage) at which battery wilting becomes an issue. The same goes double-plus for pure electric cars, which become functionally useless when the battery pack wilts.

In general, I would not want to hold title to a hybrid with more than 100,000 miles on the clock or one approaching ten years old.

You might want to give some thought to selling or trading yours in while it is in good functional shape – and before it becomes necessary to spend a lot of money to return it to good functional shape!

. . .

Got a question about cars – or anything else? Click on the “ask Eric” link and send ’em in!

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  1. Is there a mod, whereby you simply remove the Prius’ battery pack and run solely on the gas engine? I’d wildly guess you’d still get 30+ mpg with that set up. (I’m sure this has been done, but too lazy to search it out….)


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