After ~13k miles I've never had the computer tell me I'm doing more than 12mpg in my 50i. Most often it's in the 9-11 range.
Window sticker: 16 combined city/hwy | 14 city | 20 hwy | 6.2gal/100mi
Tank capacity: Approx. 22.5gal. (per owner's manual)
My commute is a fairly even split of city/hwy imo. Those familiar with Chicago - I live on the Northside and take Lakeshore from Hollywood to North and then it's just a few blocks of stop and go from there. (7.9mi fwiw). Mornings typically have some traffic but evenings allow for 40-60mph on Lakeshore. Sport mode on the on-ramp but other than that I'm in D the whole time
I recently reset my trip computer at the pump following a fill-up. Keeping a close eye on the fuel gauge, I checked back in on the computer when the dash told me I had run through half the tank.
Computer: 109mi | 10.9mpg | avg speed 16.1mph (Anyone know if the mpg and avg speed are just the most recent start to stop or averaged across the entire 'trip'?)
Approximate calc using tank capacity and miles: 9.7mpg
So what do you think? Is it realistic to look at estimated fuel consumption based on the tank capacity and what the dash gauge tells us? Considering it's not a laser accurate measurement, is ~1gal/mi off what the computer says acceptable? How about ~5-6gal/mi off what they tell us on the sticker?
I understand a more accurate way to do your own mpg calculation would be to fill up - reset the trip computer and then at the next fill up look at the exact gal you just put in and subtract from 22.5 and then take the exact miles off the trip computer. I've just kicked off a second analysis on fill up this morning.
I may spark up a new thread on this if this one doesn't come back to life.