I average about 44Mpg(UK) but I make Big Kev look like a waif (6'4" 25 Stone) and I have a very heavy throttle hand.
Last summer after running her in, still using the stock screen and with panniers and topbox fitted I did an extended run at high speed.
Over 1 hr @ between 120 & 155Mph (speedo) whilst playing with a ZX12R on the A3 Autobahn.
At one point I switched to Current Mpg and was surprised that at a constant 140 she was still getting 35Mpg(UK).
Averaged 38Mpg(UK) over the tankful (180 miles).
The ZX12R pilot pulled in at the same time as me and we stood there filling the bikes with great big stupid grins on our faces.
I think he enjoyed playing with me more than playing with the SL55AMG he'd been teasing when they first came past me.
We left the AMG for dead and never saw him again.
