I filled mine up last week and only averaging 14 in the city. But its winter and has warm up time and such, but I still think it should be better. I have never put any injector cleaner in but I plan on it soon., My air filter is new also.

 

You cant go by instant economy thats not a true reading.

 

crankcase flush,clean oil pan, i did that at my autoschool and those 2 alone made a big difference,,a guy in my class took our his backseats and passanger seat,nutjob,but he does gas every 2 weeks instead of 1
Le Dude