When reporting your mpg for the database- do you give a lifetime average (i.e. you do not reset the mpg calculator on the A/N system), or do you reset it for each tank of gas and report the mpg?

June

 

Generally you report your average tank by tank. I reset my trip meter at each fill and report miles travelled divided by gallons pumped. I record the car's calculated average from the display in the notes for information only.

 

I'm doing it per tank. As a new member, and new hybrid owner, I also wondered whether calculated wasn't perhaps more accurate than the the computer. Interestingly, at a new owners orientation I attended this evening the Toyota service manager said this wasn't necessarily so. He said the pump won't shut off at exactly the same amount each time. He also said the Prius has a bladder (?), or something flexible, for a fuel tank, and consequently variations in how empty it was when you started to refill, temperature, etc. could cause slight variations -- he suggested the computer was probably as accurate as hand calculated.

 

I checked my spreadsheet last night and noted a ~2.5% difference between MFD and hand calculated fuel economy for the Prius over the last few thousand miles, with the MFD being optimistic. In the grand scheme of things I don't think it matters which one you put into the database as long as you are consistent about doing it the same way every time.

 

Good points. I really wondering if anyone cared if it was a lifetime average or per-tank average as it seems like that would/could make a big difference if your mpg varies alot from tank to tank.
I have not really figured my mpg out 'by hand'- mostly because math makes my head spin.
I would love to hear from other FEH owners to see what they think about the accuracy of the mpg estimation on the audiophile/navigation system.

 

The GreenHybrid.com database, data entry form does the math for you. Just keep the gas receipt and enter the miles and gallons. Click on the "Compare" tab to see how to start it up.

Bob Wilson

 

Tank by tank.

I don't put much credit to people who do lifetime averages, since it's a single data entry, and they can say whatever they want. (Check it out, many of them don't update ever, so they enter their data once and leave essentially.)

In addition, tank by tank allows the graphing system to work, and gives you a feel for the trends of the vehicle, and to give you something to compare against.

 

Nice to know that it will do the math for me-otherwise, I probably would never do it.
On a frustrating note, my husband had the FEH last night and filled it up and did not keep the reciept. Guess I am going to have to rely on the NAV for this tank.

 

Don't get too worried about missing a tank or two. The value is getting a trend, a statistically valid sampling. Just make a note about the that entry and life is good.

Bob Wilson

 

reset each tank of gas