Computer mpg readout

[charlier180]

:iagree: with charlier180. I keep mine on a spreadsheet. My spreadsheet keeps track of the mileage on each tank plus a running average, best and wosrt mileage. Very simple formulas. If anyone likes, PM me your email address and I'll send the blank Excel sheet over.

Uneek, I also have two other columns in my spreadsheet.
One that records the dash MPG readout and one that calculates the diffrerence between the dash readout and the calculated MPG in the spreadsheet.
That is where I get the 12-20% higher numbers from in my post above.


BTW, interesting observation t65k3. I have found that the MPG Sweet Spot for my 4Runner is 55-60 mph in overdrive. Of course at that speed in overdrive my V8's RPMs are also lower.

 

[t65k3]

I noticed one thing last night.

After about a week of drving in town, the average mpg dropped from 22.0 (mostly hwy) to 18.9. So when I put in about 6 gallons of gas, the distance changed from 32 to 133. Only an increase of 100 miles, which says approximately 16.6mpg.

Then I drove it on hwy, the odometer read 12 miles while the distance decreased from 133 to 126. That's a big difference, and lots of factors come into play. When it calculates, I think it uses the average number since last reset or even last mpg from certain numbers of miles. Average number makes more sense.

To charlier180:
You are right. I think low rpm is the key.
The numbers I mentioned were for reference only. Different weather, traffic, and other stuff could make all the differences.
When I drive on hwy, I usually pay attention to the rpm after I go above 70mph. Tune the gas up and down in order to achieve lower rpm.

 

[jonz]

I replaced OEM Bridgestones after 80K miles (great tires !) with same size Michelins. Before the new tires, actual MPG calculated at fill up was about 2MPG below onboard computer....actual about 19 - 20 vs 21-22 on computer. With the Michelins. Computer and actual MPG decreased by about 2MPG. Turns out the new tires are bigger, even though size is supposed to be the same. My speedometer is off by about 7%. I used GPS device and determined that 75 on speedometer is actually 80MPH and that 100 miles on odometer = 107 miles on GPS odometer. Now I multiply mileage by 1.07 at fill ups and divide by gallons. I'm right back at 19-20 MPG.
Mine is an 04 2wd with V6.