Ok, thought I'd see today how good a fuel economy figure I could get.
Route was as shown below from my TomTom Go - mostly A roads, the odd bit of B road & some Urban. Temperature was between 7 and 13 degrees C, mixture of rain (

)& sun (

). Climate control was on all the time at 21-22 degrees and used cruise where possible.
Roads were quite busy at times so average speed was only about 30 mph, and a lot of the time was spent sitting at 45-50 mph. There was the odd overtake which temporarily dropped the fuel economy back a bit - Wasn't driving with light feet all the time !
I know that the trip computer reads higher than the actual fuel economy, but reckon the actual was about 47/48. I also reckon that the economy will improve with mileage - Only done just over 2000 miles so far.
Still, I thought it was impressive - not sure I could do it all the time as it took a fair bit of concentration and anticipation to maintain momentum.
For the record, the motorway cruise from Glasgow back home dropped the trip computer average to 48.2