Are you sure there's a problem because your fuel mileage dropped.

Before you spend any real money or time fixing something that isn't broke make sure that there really is a problem.

I've been getting what I consider low mileage for the last two or three months on my 2010 Prius with 99K miles.

I've been getting mid 30's for the last few weeks running around locally, low speeds, short trips and again with the A/C running most of the time.

Using top tier Shell 87, which I run exclusively, I took off for an outdoor sporting goods store an hour away from home. All interstate, cruise was set at a max of 65 mph running the A/C all the way. Speeds limits ran between 55 and 65 mph.

Round trip all highway with temps in the low to mid eighties, A/C running, I got slightly over 53 mpg as measured by a calibrated Scan Gauge. Tires are Michelin Defenders, 40 psi all around.

Yep there's no problem with the fuel mileage that I'm getting in my 2010.

Just trying to save you some time and money. A Weekend drive on the interstate at speeds around 65 mpg for for two or three hours, then check your fuel mileage you may be presently surprised.

 

The Toyota Hybrid Battery is less than three years old and has less than 20K miles on it.

 

It gets replaced next month or around Labor Day. I automatically change them out every four years.

Still good, I can hear when I shut off the car a pump under the hood run for a short time. If it starts sounding like a dial up modem connecting, the battery is not long for this world.

I had the car out yesterday running around and it was cool enough not to have the AC on. My mileage was over 50 mpg running errands that were short and medium distance in length.

Edit, took the same trip again that I did last Saturday night and the mileage jumped up again from 53 to 56 mpg with the AC on. That is around what she got at 65 mph six or so years ago with half the miles that I have on her today.