Sorry! I don't mean to discriminate against my non-US friends - I'll take your KM as well and convert it!
I've taken my first long range trip on my GTS (350 miles), mostly highway speeds (mostly full throttle most of the time) over a range of terrain but more hills/mountains than flat (max speed on very long uphills at max throttle was 60mph/100KMph). Total weight of rider and "stuff" is about 300 lbs. I could maintain about 70mph for most of the highway ride.
Over the course of my 7 hour ride, I was topping out (gas light blinks and fuel gauge blinks) at about 90 miles per tank.
Now, the "specs" said up to 70mpg, and I know riding highways all the time uses the most gasoline in the shortest amount of time.
So, I'm curious if this is similar to what others see under similar conditions.