Ok little update sat morning i put £20 in to fill it up from where it was between 1/4 n 1/2 tank,computer still said id do 315 miles to the tank, however i drove from cambridge to milton keynes and back then from camb to braintree and back, ive done 215 miles and im just gettin onto half a tank left which suggests ill get around 400ish to the tank, but yet on those journeys which were dual carriageway/motorway all the way i only managed 44mpg???
mate make sure your a/c is not on! it makes a BIG diff!