I used to have a 95 zx-6 and averaged 40-55 mpg on a tank. Now that I have a cbr600rr I can at best achieve 40-something. If I'm ripping it around I can still pull 33-35mpg. The new bikes are tuned for speed not efficiency. If I am that worried about mileage I probably don't need to be on a cbr and might hope on a standard style bike that typically average much higher mpg's.