Am gettin around 310-320 miles to a tank in ma scooby if I'm not stupid with it. You can watch the guage drop when you're giving it stick! 275 miles out of £42 worth of optimax on a stg3 cossie sounds good to me.
How big is the tank in the cossie? I think the scooby is 56L The RST is only 47L or something like that as far as I remember?!?