My R111 takes 6 gallons to fill, however, its a bike for fun so cost is not considered.42 mpg is easy enough unless you go mad. I get about 50 mpg out of the 1700 which is also quite fair.
I am a miser with the car and try anything to get those magical mpg figures.. It even has a coasting device which disengages the engine going downhill if you push the eco button on the screen.