 Gas mileage is poor in town, more like 13 than 15. Hi-way mileage is ok, averaging about 21.5 mpg. About 16.3 combined.Car is a fantastic machine and a true pleasure to drive - acceleration. anti-sway, steering control and ability to cruise comfortably at high speed are all phenomenal.  Accessories are second to none. I had a 2009 E550 before this, and IMO it was inferior to this 750i.Maybe the best car I've ever owned -- except for a 2003 Honda V-6 that was an engineering marvel engine-wise. I know potential maintenance costs could kill me down the road, but this car was pretty much gone through by the dealer before purchase, so hopefully it'll be a while before repairs start. Short story? The Ultimate Driving Machine, hands-down. I love it.Update 6500 miles and 8 months later:Car continues to be maintenance free, runs like a charm; fast, comfortable, zero problems so far. 22.8 mpg on a recent 500 mile trip averaging over 70mph. Still the ultimate cruising auto, but unfortunately attracts police at 90.