Subaru is a little behind with putting the typical new fuel efficiency features into there engines. They only just added valve timing. I'm not sure how sophisticated there design is either but I'm sure with Toyota at the helm there FE numbers will improve. Maybe they will come up with a diesel hybrid?
A love the my Scooby but compared to me civic its a pig, on the some note my WRX seems frugal compared to my friend's 03 Xterra and my boss's truck.
I consider the WRX pretty good on gas given the performance. My R foot was on the pedal all the time and my 06 WRX still returned better than 10.5L/100km for perrenial autocross-type driving :~)
Driving a 08 WRX now and it's pretty good as well but seems to use more gas when pushed...driving like a granny returns ~10L/100km...maybe a little worse because it is still <3000km.
The non-turbo cars avg about 1L/100km better from my few Subies in the past. The number may not be anything to write home, but they are very attainable (unlike my Toyota's)