There are several threads on this site about MPG's and if you look through them, you will see that some people are all over the board on where their average MPG's are. Couple of observations;
a) don't trust the electronic thingy ... they are notoriously unreliable. i use it for general comparison, but hand calc to see what i am really getting.
b) 12 is certainly on the low end ... I average 18.8 and my daily drive is about 75% city speed (30 ish) with a few stop lights and 25% highway. i could likely do better if I drove like a hypermiler, but I enjoy the Boost a little more than the Eco.
I summary, your 12 does sound off, but it is hard to say since we don't know your driving habits (the turbos are fun but not nice to the MPG's), terrain or route.