calculated vs. computer MPG - Please post your results

Do you always use 10% ethanol?

 

I've been tracking mileage for about 18 months, tank-by-tank and accumulated: 7% error overall. Guess which way?

 

Approaching the 70,000 mile mark on our Prius...

I don't have to guess I already know!

 

I've been driving my 2011 Toyota Prius Three since January 8th. I've put over 7700 miles on it during that time. My calculated versus actual mpg has been almost always a constant 5.5 - 5.9%.


iPad ?

 

LAST FILL UP
MFD = 53.0
Calculated = 50.1
MFD vs. Calculated = -2.9
% Error = 5.47%

Seeing that most of the posts I have read are showing a 5% error, wish we had an option of programing that on our computers. Heck we can plug-in the price of gas at least.

 

.

HSI - 3.7 L/100kms - 76.35 mpg cdn - 63.57 mpg usd - 7100 kms (4411 miles) on car.


ACT - 4.2 L/100kms - 67.54 mpg cdn - 56.24 mpg usd - 990.7 kms (615.59 miles) on tank.


41.435 liters - 9.11 gal cdn - 10.95 gal usd - $58.80 cdn @ $1.419 cdn per liter !!!

.

 

At today's x-rate in Germany we are today at exactly 8$/gal (or 1.6€/L)...

 

(This is my 4th tank in the car)

2012 Prius

491.9 miles
8.624 gallons
Displayed 60.9
Ave speed 31
Actual 57.03
Difference -3.87 mpg or 6.79%

The miles to empty display showed 92 miles to go, but I wasn't about to push the car for another days commute. (@75 miles RT).
This pace may be unsustainable, but at least in a few years time I can look back at these numbers and be quite happy! If it levels off considerably to the mid 40's I would still be pleased.

 

2012 Prius
452 miles
Displayed 52.2 mpg
Calculated 48.7 mpg
Error 7%

 

MY first tank in the new car:



507.3 miles car took 8.93 gallons of fuel

HSI = 58.8
Actual 56.8

 

2nd fillup, 9.57 gallons, 489 miles: 51.1mpg
Car said 54.6 on the trip meter, seems like they should be able to get this right, don't you think?

 

:amen:

No Sh--!!!

HSI - 63.57 mpg usd

ACT -56.24 mpg usd

Fill up #9

opcorn:

 

Fill up = 10.021g
Computer mpg = 56.1mpg
Odo = 0 - 535mi from full to empty(0 mi left)
Calculated = 53.39mpg

90% Eco mode and 10% Normal mode.

 

First fill up:


335 miles car took 6.71 gallons of fuel

HSI = 51.1
Actual 49.93

 

my 2nd tank of gas

2 pips left
Miles: 501.1
gallons:8.328 to 1st click
computer: 60.9 mpg
calculated by Fuelly: 60.2 mpg
decently spot on. My last tank the calculated was about 2mpg more than what was on the display.

Used NON ETHONAL 89 & filled with same at same station.

 

I have a theory on this. The HSI only updates when you're actually moving, or at the very least when you're out of "park". So perhaps when you're in not moving but the ICE is running, you're burning gas that the HSI doesn't count towards its MPG calculation.

 

Nope. The HSI Does update when you are not moving. I have to take a ferry everyday. On really hot days I will leave the car in ready position. It remains in ready position for about 45 minutes. It is not unusual to lose .4 mpg by the time I have to exit the ferry.


iPad ?

 

I'm guessing you're in Park and don't just have your foot on the brake the whole time? Oh well, so much for that theory.

 

Yep, I'm in park. It really costs me more than .4 when I consider my car has to recharge the battery totally when I get off the ferry. Obviously the .4 is not totally accurate because it would be dependent on how many miles I already have on the current tank.

Personally I think the difference is in the pump stopping point, and because of such a small tank. There can be more than a .5 gallon difference which is really significant I'm going to start filling it to the top for a few fill-ups just to see how much difference there really is.


iPad ?