50 Mpg to 45.9.....why?!?

It's that weird computer MPG display. I don't have much faith in it. My 2016 Three does that sometimes too. AC on, AC off, doesn't matter. The MPG display jumps all over the place. So I just happily blast my AC at will, and don't worry about it.

The MPG display also acts funny if I refuel at 1/2 tank. Or 1/4 tank. Or if I add a little more gas beyond when the pump clicks off. The display can show 61 MPG, and a couple hours later it drops to 52. Then sometimes 49. Then the next day it's up to 54. The heck with it! The only true accurate miles-per-gallon reading comes after I've gone through a whole tank, and then do a calculation. I never rely on the computer display... especially when doing short trips. It's meaningless.

 

I have something on my mind, may or may not be what's affecting your mpg: ethanol vs ethanol-free fill up??

 

I'll say it again... I just drive it. I refuel whenever I want, blast the AC as much as I want, drive in PWR mode as much as I want (which by the way, my Prius gets the best MPG -- go figure) and I don't concern myself with the numbers on the display.

Maybe I'm totally wrong. But in my humble opinion, WE, as Prius drivers, driving a great economy car should just be able to relax, enjoy the ride, and no longer concern ourselves with MPG figures. But that's just me. I understand that some owners like to constantly track it, log it, and do it as a hobby or something. Always playing that MPG game. (I got bored with it after 2 months of ownership. )

 

I just drive mine. Easy, it's no American muscle. If I want fast and gas guzzling, I'll jump into a different vehicle.
I let the computer figure out how to do the 50 MPGs.
End of the day, its there! Or 48.7

 

My daughter practicing her driving today
109.7miles
52.1 MPG
she hasn't the slightest inclination to maximize MPGs but the PRIUS knows what needs to be done
AMAZING...

 

My average MPG on the car computer is always 2-3 MPG more optimistic. I use fuelly to keep track of my MPGs accurately.

 

That's pretty amazing, driving training, especially a lot of parking practice, can be rough on mpg. House hunting is bad too, lol. Oh, and Christmas light touring.

 

It is "MILES per GALLON".

Driving too fast or against a head wind will increase the gallons for the same number of miles.
So will going extremely slow, like when caught in a traffic jam; you eat gallons running the AC and other accessories while making no miles.
So will running the AC while stopped.

Yours is about the millionth post about what really is a relatively minor change in gas mileage.
Most of the time, it goes away or averages out.
If there really IS anything wrong, it will get worse.

 

Exactly! My 2011 is the same. By the end of every tank, as long as the display days at least 52mpg, I know I'm in 50mpg territory.

Love Fully btw, just wish they had a true mobile app instead of the mobile wrapper they currently offer.

Posted via the PriusChat mobile app.

 

Like everyone has said, the MPG gauge on the car isn't the most accurate. A/C makes a BIG difference in MPGs. Here's a chart of my gen 2's gas mileage from last year's summer compared to this year's winter using the Automatic OBD II adapter. I always have the A/C blowing cold, but stronger A/C uses more gas, so in August 2016 my MPGs were really bad. It was hot. January is less hot at around 65º-70ºF and I got 11.5 MPG better in that month. I used less A/C.



As you can see, I don't have a light foot either. Just remember you are driving a great car that will get better MPGs than a comparable Corolla. I'd rather be comfortable and shave a few MPGs than sweat in the car while delivering pizza.

 

^ That's exactly how I view it.

Somedays I really try to eek out as much MPG as i can, particularly when no one else is behind me. However, most of the time I just drive like I would a regular car because I know im already getting better MPGs than the 13-16mpg i got in my mustang, and better MPG than the average compact car.

 

End of this month will be 2 years that I have had my 2015!! Bought it new. When I first got my car, I was amazed at all the gizmos and of course, my mpg. Now that I have gone through 2 seasons, I agree with most above. Right now, we are having a very humid summer (for us so cal folks) and I have been running the AC more. I can take hot weather, but humid hot weather makes me sweat a lot. I get athlete's foot, as well as other bodily bacterial issues that come with humidity. So, I run the AC. Mileage has gone down to 42-43. Was at 47-48. I only have 26,000 miles on my car so I know nothing is wrong. So, I will turn off the mileage indicator so I won't keep tracking what I am doing. We Prius drivers are addicted to trying to get better and better mileage. But I have to remember, I never got this type of mileage out of any other car I have owned. And I look forward to just servicing the brake caliper pins at around 50,000 miles, not replacing rotors and pads.