calculated vs. computer MPG - Please post your results

On a car advertised to get better than 50 mpg, they guessed wrong.

 

Can you say "...INFLATED mpg readings..."? Sure you can!"

 

total miles @ 187 miles, the car show 43 mpg.. this is including 70% highway mix, filled up the tank, 4.5 gallons under $10 Hopefully the miles will increase after the initial break in period..

 

A couple weeks ago some jerk rear-ended my 2009 Prius and totaled it. At a bit over 65,000 miles, it had 48.06 mpg (based on total gallons bought/total miles driven), and 48.89 mpg (based on the MFD)--a difference of 1.7 percent.

I just bought the first tank of gas for the new 2015 Prius the insurance company (mostly--I had to kick in around $8k) bought me. After 462.1 miles, MFD says 55.4 mpg. My gas receipt indicates 53.6 mpg, a difference of 3.4 percent. Although I don't know if the salesman topped the tank at the same level I do--it would take only a 0.29-gallon difference to account for the differences in fuel consumption calculations.

At any rate...daaaaaaamn, that's pretty impressive! My Gen-III is showing 12 percent better gas mileage than my Gen-II.

 

With over 125,000 miles on our 2010 Prius III the fuel economy display is off by 3 - 4 mpg over reading. I installed a scan gauge II which now is under reading. So if the scan gauge states 50 mpg it is closer to 52 mpg. The Prius computer is probably reading 55+ mpg...

 

Over last 20,000 miles (yes, >20k) Prius reports 58.7 mpg.
My calculated during this period is 56.3

So difference is about 2.5 mpg

 

2015 Persona with stock 17" wheels...with 8k miles on her.

Just filled up. Had a good tank and a few real high mpg trips.

437.9 miles
47.4 mpg displayed
45.32 mpg calculated.

One of my better tanks, and ac has been in use most the whole tank as it's been hot. I try to use auto though...

And one of the lowest variances, 4.5% right about

 

I have experienced swings in hand calculated mpg, but I attributed it to living in Oregon and not being able to pump my own gas and top it off properly.

SM-G900V ?

 

550 miles on my 2015 Prius III. First tank displayed 49.3mpg, calculated 49.8mpg. This includes one 200 mile round trip fully loaded w/ passengers and luggage. Very happy with those results. My highest commute mpgs are 53.5 and 57mpg. Loving this car.

 

Calculated MPG is higher than computer display? First time.I've never seen that. Usually computer display MPG is higher than calculated MPG

 

Exactly my thoughts as well. My Prius is modest.

 

Been doing great with my MPG, especially with the warm weather we've been having.
Even with 17 inch wheels and a bad set of tires.

 

I think my car is going haywire, getter better fuel economy when I run the air conditioning unit versus not running the ac unit. Here is my milage from about 2 days ago.

 

Here are my readings for the last few fillips. Summer makes a huge difference:

 

I can't say this is so without more details, but you do know the battery pack is COOLED by the cabin air, so you really need to have the AC on and set to a reasonable temperature (70-75) so the battery pack doesn't overheat while driving. I hear that negatively impacts fuel economy. Once the cabin is at a desired temperature, on AUTO the AC normally powers down to only what's needed to maintain the temperature...saving energy in the process.

Besides, you paid for the AC....enjoy it.

 

I'm monitoring battery temps, and see no drop in temps with AC use.

 

oohhh That bit of info is gonna stir up some opinions......

 

That would make sense, IF your battery temperatures aren't high enough to motivate the battery fan to crank up to a clearly audible speed. I'm a little surprised that my battery fan never speeds up over a very low speed even on hot days. (I can just barely hear it from the driver's seat only if everything else is off and I lean as far as possible toward the right rear.)

 

Let's face it it is pretty pathetic that Toyota programs the computer to inflate the computed mileage although I am sure they are not alone in doing this. I have owned my Prius III since new (41K now) and periodically compared computer to actual and every time I checked the computer was at least 4% "optimistic" compared to actual. My son has a 2009 Prius II with 110K and his discrepancy is similar to mine.

 

I hit the 15k mile mark about two weeks ago! After about 30 fuel-ups, the difference on mine seems to consistently sit between 4-7%.