Fuelly Forums - City/Hwy based on time, miles or fuel?

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I just started using this method as well.

Quote:

Originally Posted by B3NN3TT (Post 173377)

This is my method:

It's a subjective measurement, to be sure. But the EPA considers any driving over 48 MPH to be "Highway", and anything under 21 is considered "City" driving.

The 27 MPH in between 21 and 48 is where your percentage lies.

If you want to use those parameters, you can easily calculate Highway percentage so long as your vehicle offers an "Average Speed" measurement.

Take your average speed for one tank, and subtract 21. If your average speed is under 21, or over 48, then stop here; you have either 100% City or 100% Highway, no math required. If your average speed is somewhere in between, then take that difference and divide that number by 27 (the difference between 21 and 48) to get your Highway percentage.

Make sure to reset your average speed reading at each fillup.

For example:

At fillup, my average speed reading for this tank is 41.

41 - 21 = 20.

20 ÷ 27 = 74.

My highway driving percentage for this tank, according to the EPA, is 74%.

Quote:

Originally Posted by B3NN3TT (Post 173377)

Thank you. I have added this calculation to my tracking spreadsheet.

This should be a fill box to just plug our average speed into fuelly :)

An average speed entry would be nice, but that isn't the same as a city:highway split.

Quote:

Originally Posted by trollbait (Post 173722)

An average speed entry would be nice, but that isn't the same as a city:highway split.

No, it's not exactly. But the point is that is is not a subjective number; it's consistent every time. If you can't evaluate these things mathematically, you're just guessing.

For those of us who have average speed readings, a box in Fuelly to enter that in AND HAVE FUELLY CALCULATE THE CITY/HWY % would be great. But, since that isn't likely to happen I calculated the figures myself for all average speeds between 21 and 48. I just look at my chart and enter the calculated % into Fuelly for each fill-up.

This is the quantitative method I'd hoped I'd find. Alas, I have no avg. speed function in my car. I'd have to resort to my Speedometer App which uses GPS to track time, speed & distance ... but it would get tedious, and I would surely get forgetful, having to start and stop an App every time I start and stop the car. At least I know it can be done!

I run mine based on average speed. I read the write up here I believe. 20mph=100% city and 50=100% highway. Run the math at each fuel up to determine percentage.. Meaning if you had an average speed of 35mph, you would report a 50% city usage for that tank. I don't think it's a perfect method, but there is no way I can track usage based on miles driven in a city or highway scenario. It's consistent across fuel ups and simple to calculate, so it's what I use.

I just roughly guess % based on city/hwy miles for my daily drive.

Outside of Fuelly, I have taken closer notes on trip FE versus # stoplights, outside temp, net headwind speed and route used. Those four factors account for ~85% of FE variation seen. Driving conservatively coupled with warmer temps has helped get FE up from 37 to 46 mpg trips.