In 16,018 miles I have averaged 47.26mpg with a best tank full of 54.13 and a worst of 31.41...
That's real life... not these single runs crawling along at 56mph, down hill, in the slipstream of a 48 tonne truck at 3 a.m. 
Worst tank - was that a lot of fun or stuck in horrendous traffic?
My best has also been about 54, going from Newcastle to Leeds and back taking care of about 40% of a tank of fuel doing an average of 57mpg for the 210 mile round trip. Don't think i've got less than 39mpg on a tank though, even when hammering it. I bet I never see 39mpg with the R on the best tank.