It's still pretty cold there, I suspect, so hold on until you see your warm weather mileage before passing judgement. Do you drive a lot of very short trips, like 5 miles or less? If so, that and the cold weather explain your very low mileage. Cars work best when warmed up, so if it never warms up you never see peak mileage. Just the nature of the beast. On the bright side, shorter trips mean less driving and less fuel consumption overall.

Care to talk a little about your usual driving enviromnent?