If anyone is interested, here is the mileage data fromaround 2000 - 7000 miles on my odometer. I've graphed the gas mileage I recorded vs the average speed during the interval. As you might expect, the mileage increases as the average speed increases. Most of my points represent about 250 - 300 miles of driving.

The mileage varies from a low of about 15 mpg for pure city driving, to a high of close to 25 mpg for pure hwy.

 

nice job !

 

Did you calculate the actual mileage, or did you take both the fuel economy and average speed data off the trip computer?

The reason I ask is because I have found that the fuel economy, and therefore the miles to empty, calculated on my U.S. 530i trip computer is so far off as to be totally useless. For example, my actual fuel economy calculation (all highway miles) was 29 mpg, while the trip computer indicated 37.8. I have a hard time believing that I am the only one who has this problem, but I have posted this a couple of times, and no one has come back with any similar complaints or fixes. My dealer assumed that the upgrade to 13.2 would fix it -- it didn't. No big deal, but I've had several other non-BMW cars over the past 15 or so years with this feature, and I was always surprised at how accurate they were -- not my bimmer!

 

Good stuff. I have taken data for mpg that the computer shows vs. calculated mpg.
The deviation is ~ 10-15%, but its not systematic.
I get ~ 18 mpg for city and ~ 26 mpg for freeway driving.

Jochen

 

Just a thought, but I remember some other members were getting really high numbers also. I beleive that it was because there was two gallon settings, Imperial and US, or something like that which would effect the computers calculations. You may want to double check yours.