haha
its 42 or 43 mpg!
i have got that a few times now driving from Reading to Nottingham
it does mean driving like an absolute granny all the way up the M1 (like 60-70mph) but it does do it, and when i arrived i fiiled the tank back up and calculated the mpg from that and it was almost spot on!!
they can be economical, but mine is rarely over 32mpg through normal driving