I did a journey to a mates house the other week, took some resin to his house to fill a cracked windscreen,,,
any how i had just filled up at the garage at the top of my street and reset all the settings on the trip computer, which i do after every refil.

did the round trip there and back which comes to about 35 miles,,, dual carrige way and B roads nearly all the way there and back

When parking the car back on my drive i noticed the milage on the trip screen,,, this is the most its ever shown after any kind of trip,,, when i say trip i mean not to the shops up the road but more than say 10 miles.

i was a little stunned to say the least,, i have had it at 60-68 ish on trips to the coast etc.

I got 74.3 on the way back from the petrol station a couple of weeks back. But of course the engine was already warm and it was just 15 miles of light traffic on a B road, pretty sure I couldn't average it over a tank though lol.