I've been getting right around 40mpg this year. Last year I saw closer to 50, that was with a brand new air filter and spark plugs at the correct gap and very conservative riding. This year I ride way harder than I ever have so I expected lower mpg but so far it hasn't varied too much. I also run the specified tire pressures F36 R42 in Dunlop Sportmax Q2 tires and 87 octane in the tank. I used to run 91 in my bike last year but having read on how it has little benefit I dropped back to 87. That and running 93 in the WRX it's nice to be able to spend a bit less on the bike. My rpms usually fall in the 5k range. I cruise in 2nd or 3rd at 30mph, and anything above 50mph I'm in 6th gear unless I'm having an Isle of Man moment.

 

I tried using low grade 87 and I got 20 miles less per tank, I went back to 92 and get
better milage, starts quicker and the throttle is way smoother.

 

I have a 02 f4i and when i first got it i was getting mid 50s consistently but i was always riding at a low rpm. more recently i get mid to high 40s always, i never get below 40 not once in the 3 years i've had the bike and i don't ride like an 80 yr old. i do still have the stock set sprockets sizes tho(not an acceleration package) Beats 20 MPG in my mustang gt!

 

my guess is the 87 was 10% ethanol which kills mpg by 2-5 mpg. Getting harder and harder to find ethanol free gas

I range between 37-42mpg depending on fuel type and riding style.