My 2007 FZ6 will get mid 50's on the highway, as long as I stay below 80 mph. Around town I get 41-44 mpg, and if I am running it hard on the back roads I have gotten as low as 32 mpg. Motorcycle aerodynamics are not that great, especially with a rider sitting in the path of the wind. If you put my FZ6 powertrain in a aerodynamic 400 lb vehicle, you could probably get pretty good fuel mileage. As it stands, I have no complaints with my bike, for a 600 cc four with 100 hp and a 14,000 rpm redline, the fuel economy is actually pretty good.