Maybe should start a thread on this but the best I've seen on mine is about 41mpg, and that was downhill on the M8 when the traffic conditions were holding me to about 50mph. It only held at that level for a few miles.
I'm averaging about 32mpg overall. My daily work run is about 10 miles straight on an A road, no starts and stops, and I don't often get above about 32mpg.
I'll start a new thread, it's interesing.
Rolfe.