I'm now on my third fill up.
It wasn't full when I got it so I've been monitoring it since I fully filled it.
The gauge is not very linear and neither is the miles left to fill up calculation in the trip computer.
I just get three return journeys, Anglesey to Glyndwr(66 each way), with enough left to get to the garage to fill up.
It's nearly all dual carriageway apart from Dobshill to Wrexham and apart from the few roundabouts and Rhuallt Hill it nearly always stays in 5th on the dual carriageway. Speed for that section is usually 65mhp on the dash, which equates to 60mph on the m+m.
Miles wise it seems to be coming out at about 390miles until the light comes on with about 40 miles (computed) left, although I wouldn't want to push it beyond 20.
So I guess I'm getting about 400 miles to the tank, although I'll continue to monitor it as I think it should get better.
I run it using the gear change indication and also on cruise control, I think it's slightly better driving it manually.
It's a bit too early to see if it will improve.