hello all,this is my second week with the 2.2 sri,after moving over from a ford,the thing i cant understand is after filling the ford up with fuel,i could travel nearly 70 mile before the gauge started to move,on the vectra the needle is on the move nearly straight away,theres no leaks and last week i averaged 37 mile to the gallon,which was mixed driving,i was over the moon with that but is the gauge reading normal or do they all fall quick,thanks in advance.