Bob welcome to our club!
I am sorry to hear you are not real satisfied right now.If your G35 owners dont see this post too soon use a NICO search for "g35" (red buttonon top right) and find them that way.You can then email them via their profile (unless they disabled that function).We have a couple of Coupe and Sedan owners and they all seem to love their cars so far.
Fred...
PS: Some states have reformulated gas, which will push milage below EPA figures, also winter gasoline is reformulated even further, the greater use of heaters/defrost etc can do the rest.