So last weekend I drove to Nebraska and back - round trip 650 miles. No, I didn't get back on the same tank, but I came close. I filled up at home and didn't have to pull over for 575 miles.
I saw the fuel consumption graphs on the VM Motori website that showed the minimum at 2000 rpm. I realize that graph is probably full load BSFC, but oh well. I also have the InMotion Stage II tune which complicates things. So I set the cruise control at 2000 rpm which equals 69mph for me on the GPS, and after the first 325 miles the EVIC showed 32.4 mpg. It's usually within +/- 1mpg of hand calculated. Realize that this is downhill the whole way, from 5000 ft to 2200 ft. On the way back there was a stiff headwind and of course going uphill too. The low fuel light came on at 550 miles and I pushed it for another 25 before stopping. The EVIC read 28.8 mpg and hand calculated was 28.
What's weird is that after filling up I was sick of driving so slow, so I set the cruise at 80mph, and by the time I got home it read 32.4! No joke! I'm still scratching my head over that one, but maybe with the tune the engine's new sweet spot is a little higher.
Tires were at 42psi and side mirrors were folded in the whole way for lowest wind resistance.
10 oz of PS gray bottle were in the fuel.
The most fuel I have squeezed into the tank was 22.5 gallons, so if I were to leave a 1/2 gallon cushion, 32mpg should get me 700 miles. The stars would have to line up right for that one though.