Well, at risk of being run down by truckers for past tank of fuel, I tolerated 55 mph to/from work (60 miles each way, altitude gain/loss 2000 feet from Flagstaff to Winslow and back), and resulted in 25.68 mpg hand calculated. Scan Gauge II was giving me 26.4.

Well you beat me now... My top was 25.3 hand calculated... As for the mild offset it could be a slight calibration error or speed calibration is off slightly... Either way it will effect the out come...

My SGII speed, if I set it at 5 results in less miles driven than my GPS odemeter, and if 6, then more than GPS odometer. Can't seem to get the miles driven to agree with GPS. I find myself changing the speed about a 1/2 way through tank to get miles to agree, so I can see the potential for error, but it's pretty close.Was your 25.3 done at 55? If not what speed did you average for that mileage. I don't know how much longer I can tolerate 55 on the interstate, it's eating into my time, also, have to leave for work 15 minutes earlier than before.

I just went went to michigan, today, as in right now lol. I screwed up and ended up being around 600 miles on 3/4 tank, maybe a little more. I did 80 the entire way. Will be interesting to see what I get. I am gonna go 50mph for at least 200 miles on the way back. Should have numbers for you all by monday.

My SGII speed, if I set it at 5 results in less miles driven than my GPS odemeter, and if 6, then more than GPS odometer. Can't seem to get the miles driven to agree with GPS. I find myself changing the speed about a 1/2 way through tank to get miles to agree, so I can see the potential for error, but it's pretty close. Was your 25.3 done at 55? If not what speed did you average for that mileage. I don't know how much longer I can tolerate 55 on the interstate, it's eating into my time, also, have to leave for work 15 minutes earlier than before.

Well I did a trip from Cascade, ID to Stanley, ID then down to Boise, ID. This is all winding canyon roads and hill climbing. When i could better I would typically limit out to 55-60 MPH. 153,549 - 153,197 = 352 Miles / 13.915 Gallons = 25.29 MPG (Copied from my fuel logbook)

Just got back home, finally. I wasn't able to fill it up after the 80mph run since it costs half my soul but I am going to judge it was around 33 gallons for 650 miles so thats 19.69mpg. Way over my 2mpg/5mph theory which would have theorized around 17mpg. I really did beat the crap out of it so I don't see how it gets so good. Musta been the 2 stroke! On the way back I did 60 the whole way and, not sure what it got since I didn't top it off but from what I could tell, I think it would be pretty close to the expected 25mpg. I am going to top it off for the weekend and run home and back at 50 since traffic was a little too much to try it on the way back here today. That will get me 180 miles worth of testing on some hills and curves.