2012 Suzuki V-Strom 650, 90 degree v-twin, 6 speed, chain drive, always run with the Givi Maxia 55 top box. 65 hp, 42 lb·ft torque, 430 lbs dry, 470 lb with coolant, oil and full tank of 87 octane gas. Rider is just a bit above 210 lb with all the gear on.
For normal riding my average moves between 57 mpg in cold weather and 62 mpg in hot weather. Best ever has been 67 mpg in hot weather on country highways riding a relaxed 40 - 60 mph, worst has been riding low 50°F range into a 15-20mph headwind at 80 mph, mileage went down to 45.5 mpg.
I have run 320:1 MMO and 640:1 Motul Powerjet TC-W3 in the gas, but I don't think it affects the mileage. Now on my 2nd OCI of Motul 300V 4T 10W-40, and I think it's had a very small improvement on mileage, probably due to it's relatively low 12.15 cSt 100°C temp viscosity. On the other hand, it seems to take a little longer to fully warm up and get to the best mpg's, maybe owing to its better heat transfer ability or its higher density than Group I - IV base oils.