This tank of gas, I'm averaging 49.2mpg. My 8500 mile average is 43.9. Last week I ran it flat out at 4am between Anapolis and the DC beltway. Topped 118mph. It was over 5000rpm almost the whole time.
I have tried to run a consistant 85mph, but it drops to around 28mpg average.
To get my best fuel mileage, I do basically what double trinity does. I use the downhills to my advantage. I do my best to keep the bar at 60mpg. Sometimes I can get over 80mph and still keep it at 60mpg. When I hit the uphill, I try to keep it over 40 on the bar. I cost a bunch in traffic to keep my battery plump. Sometimes I draft off semis to my left. I get in real tight to get as much dead air as possible. I've seen 75mph and over 100mpg on the flats. I would never draft like that in any sort of traffic. Its dangerous as it is.