34mpg average so far 2014 diesel

My 2014 Mazda 3 would get about 30mpg average. 33-34 is what I figured I'd be getting with the Diesel Cruze. I live in Hawaii (island of Oahu) were traffic and short freeway trips are the norm. So, MPG is what I expected but not as hoped. Also when the wife drives she uses the Diesels low end power and burns some diesel.