I have a 2011 Prius C. I've gone from an average of about 48 mpg down to a current 36 mpg in a matter of a month. WHAT could be causing this? This car gets the best care, always on schedule, at the

Asked by Aug 22, 2016 at 08:16 PM about the 2011 Toyota Prius

Question type: Maintenance & Repair

Mileage started dropping about 6 weeks ago, from 48 to 44, then to 42, now at 36 mpg.  Dealer doesn't want to hear it.  I think it might be the big battery, and they don't want to replace it.  Not sure, of course.  Cannot find the Trim on any of my paperwork.  Don't know which it is.  It's a 5 door hatchback.  

10 Answers


Did you recently replace the tires??

No new tires. Tires are in good shape. I guess I should have mentioned that I have about 77,000 miles on it now.


Of course, how you drive makes a really big difference.... How many miles are on your car? I cannot imagine that your battery is bad considering you have a 2011.. we have a 2009 PRIUS. We just replaced the tires with Continental energy saver tires...it handles better, but lost about 1 or 2 MPG.

I drive the same way I've driven since I was 16. Not any different from the time I purchased this car to now.


We have 68000 miles on our 2009, but, I've heard people who have 125,000 miles or more and no large battery issues.. By the way, Toyota warranties the hybrid battery for a long time, check the website....In California, our hybrid battery is under warranty for 10 years or 150,000 miles... It does vary in other states... I would think you're covered.... I'm sure that you can get the hybrid battery tested?


So, you purchased your car brand new?


Take a look at your owners manual.... If you can't get anywhere with your local dealership, call the corporate office.... The last thing Toyota wants is disgruntled clients, especially with the Prius... One thing we have had trouble with is the struts....had to recently replace them, NOT a very strong part of the car. After we did this, we noticed an increase in MPG.


Found this for you on the Internet------ "The battery pack in any hybrid Toyota is warranted either for 10 years or 150,000 miles (in states with California emissions laws) or 8 years or 100,000 miles in all other states." And, he adds, "There's no pro-rating at all. The battery will be replaced at no cost if necessary during the warranty period."May 13, 2011


If an independent mechanic confirms that your hybrid battery is failing, take this report directly to your dealership......if they still won't help you, pitch a bitch to Toyota corporate.....


If your hybrid battery is truly failing, YES, that would really hurt your mileage.....

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