Does anyone know what this is supposed to do? When I look at mine there's a chart with nothing in it. I've been driving the car for about 3 months.

 

You have to reset the fuel economy history in order for it to create a log (from the center screen, not odometer). I usually reset the fuel economy history every time I pump gas.

 

this^

it's good to reset it every time you fill up just so that you can get a good idea of your average gas, and if there is a big drop it is usually because something is wrong

 

I reset this about every 2 or 3 tanks.

Reason: I can calculate my own mpg from the gauge trip meters between each gas tank. I prefer the extended mileage average over just one tank.

 

I reset the fuel economy on the navi screen at every fill up. I reset the fuel economy on the dash every 6 months that way i can get my extended mileage average.

 

I never reset it on my navi screen. That way, I know the life time mpg average.

 

Never bother. Didn't buy it for the gas mileage.

 

Ok thanks, I'll try that.

 

And this bar graph log can be useful to spot gas usage trends. It shows a mpg bar for the last ten resets from right to left, with the most recent shaded a bit darker.

 

I didn't know that... Is there a Benchmark for the mileage reset? In other words, if you reset the LCD MPG at acertain mileage level, does it indicate that avg MPG achieved for the number of miles until you reste again or is a compliation of the resets on the odometer trip computer??? So, if I reset the LCD / Navi log at say 9,100 miles ata refill of the tank, travel 2,000 miles without resetting it, the MPG reflected is the MPG over that amount of mileage? I reset by odometer MPG generally on every tankful. Those resters are NOT affecting the LCD / Navi mpg measuerment , right?

 

Correct. The Odometer and LCD/Navi Mpg work independently. I reset the Mpg on the Navi every fill up just because I can view my fuel usage trend. I reset the Mpg on the Odometer about every six months just the get a long term MPG average. Neither affects the other. The graph on the Navi screen resets only when you reset the fuel economy on the Navi screen. It will then begin to track your average mpg until you reset again.

 

Is it possible to get at the numerical values behind each bar? I log my MPG religiously (computed by Fuelly as miles divided by gallons), and the indicated (estimated by the car) MPG never has been consistent, but I have not been recording the latter and would like to provide an accurate answer to this question by averaging the last ten tanks:

 

I started logging the indicated MPG in the notes section of my Fuelly fillups for comparison. Could others who have recorded this for a longer period please share your data? Here are the first three I recorded:

 

Your indicated and calculated values are pretty close! I wonder which is more accurate.

 

The indicated value is estimated by the ECU based on fuel injector metering. The calculated value is computed from actual gallons of fuel consumed. It's hard to fill the tank to exactly the same level each time, but over several tanks the difference averages out making the calculated value far more accurate than the indicated value. This is what makes Fully so valuable (big data!)...