I am consistently at 80 miles when the light comes on. I haven't tested how far I can go before it actually runs out. I'm a bit disappointed with this (yes, I know it is a race bike). For some of the mountain riding I do, this doesn't get me to the next gas station. 120 miles would have been the ideal range.
My one test: light on at 100 miles, 20 additional miles ridden on the HWY in 6th gear @ 80ish, 3.9 gallons went back in. So 20 miles on the fuel light is about all I’d want to go, and have to ride easy once the light comes on.