Bongo Fury

as Rita says.... the old veg oil... gives a bit of an improvement over straight diesel for me and others....
Got some from the Cash n Carry at 92 p a litre....bit of a difference over £1.44 at the pumps for rip of diesel...

Another thing to remember too is Tyres help..... just renewed all mine (one had a screw through the tread) so with one effectively "dead" and scrap and the others at 3mm.....
I changed them for another budget brand, still at 40 psi all round, an improvement on the first brimmed tank....by 2 mpg.... I'd hazard a guess the next tank, a long trip will yield an improved result too.