I recently got a 2007 Prius, I was averaging around 39-41 MPG but recently my car completely died, it did not respond to anything. I do not know much about working on cars but I went to the back and fiddled with the 12v and the car finally responded. This kind of reset my settings and Im struggling getting more than an average of 36-38. I took a look at the age of the battery and the year is 2014, meaning the 12v battery is over 8 years... Do you think the old 12v is the reason to my poor mpg?
What does fiddled with mean? Were the contacts loose? Charge battery fully then get it checked at auto parts store.
Yes old 12 volt battery can have effect on MPG. It seems you're at end of life for that battery anyways. When replacing that battery my suggestion is replace with OEM toyota battery. It's a Truestart battery which has a 7 year warranty and life span. Also the replacement battery will cost at the dealership about $250-$350. If you can install it yourself you can save money there. SM-A526U ?