In the fortnight I've had the car (GTD), I've now done ca.1700 miles, first tank, brim to initial warning light was 515miles.
That was about the norm give or take 10-15miles, until the other day when it was Revo'd ...heheheh
Very first journey after that, on a run from Dover to Reading immediately after the reflash, a run at mostly 0.85 leptons (with the obvious "testing" that needs to be done!) gave an average of 54.5mpg...couldnt believe it....with the stock map, I could just about achieve that by holding it steady at 70mph and not booting it.
Havent run a full tank through yet, but probably no worse than pre-mapping...which isnt too shoddy for +40hp/+71lbft increase.