310km out of a tank for an XR6, damn!!

I think i'd get better fuel economy out of my EL if I left it in 2 insted of D. It doesnt seem right mate, it has been said that BA do like to juice but you are getting around 20l/100km there which is not very good. Maybe a bit heavy on the go pedal?? Turbo or N/A??
From what I have gathered so far the 182 BA's avg. about 13l/100km and the BOSS BA's about 15l/100km. City driving you should get about 450km for the 6 and I'd imagine around 400km for the V8.