It seems that Fuelly is a popular tool/website for tracking MPG, but I wonder how accurate/inaccurate the dashboard-displayed MPG is. Has anyone compared MPG estimated by Fuelly and MPG on the dashboard?
Yeah, every tank I reset trip meter, note what the car's telling me, and enter it in my spreadsheet along with the accurately calculated. And enter the (real) data at fuelly. One hundred tanks (~50,000 km) tracked now, and error pretty much steady at 7.5%.
After 13000 miles on my 2014, it seems to be about 3 mpg too high, give or take a little each tank.If it shows 55mpg, the hand figured tank using same pump carefully filled up would be 52 mpg.This has happened many times.
My numbers are similar, albeit percent a bit higher. If I have a tank where the dash says 4.2 (liters/100km) it's invariably 4.5 when calculated. That was ONE good thing with our previous Civic Hybrid: if the dash said 4.2, calculated would 4.2, or 4.1 (better) sometimes. It would be dead simple for Toyota to fix. It's pathetic, like the guy/gal that keeps BS'ing about something, except everyone knows it, they're only kidding themselves.
I figure my MID is optimistic by 7% on average and varies tank to tank. How full is "full"? A significant amount of gas can still be pumped after the automatic shutoff. Pumping in "a little more" to round the transaction up to an even dollar can make a noticeable difference. An additional 0.2 gallon can knock off 1 mpg.
Okay, thanks for the feedback! I guess I will start using Fuelly and check how it compares to the car-displayed MPG. I am actually very excited! Based on the dashboard, I got 49MPG, 52MPG, and 61MPG on my most recent three long-ish trips (>50 miles). I hope they are not far off!
I've found the average displayed on the dash in various cars high, low and spot on so I don't count on them. I track miles on Fuelly for reporting and paying attention to any serious dropoff indicating a mechanical problem but other than that I just drive and refill the tank at 1/3 or 1/4 of a tank left. No chance of running out of fuel that way and I alway have peace of mind as a result.
Mine consistently claims it burns 95.0% as much as it actually burns. That's a long-term, properly weighted average that doesn't move more than a couple of hundredths of a percent with each fill-up.
