Latest update.
I did a trip to Glasgow and back after the last fill and it looks like George is not liking motorways much with my weak technique.
The first bar on the fuel gauge went at about 112 miles (120 is the the baseline) and the SG2 (adjusted after the last tank) "predicted" MPG (fillup now vs miles) is only around 55 MPG (imp), so I think this tank may pull me down a little.
I need to work on the technique for motorways (aka freeways) or any road with a speed of over 55. I did this trip with a constant throttle and a speed range of 55-65 but with the main motorway in Scotland being limited to only 2 lanes there is no quiet period to try P&G or DWL - I tried to find a truck and then followed it - not close enough to draft, just close enough so that traffic passing would know there was something slow there.
So this tank will be low unless I can refine techniques to get MPG higher before I fill up next week.
On the plus side this trip was for business which I can claim back from work at 45p a mile...
Which will go to other expenses.