So my mpg is bad and I am annoyed with it but I'm hoping that it will get better. I've heard you need to drive a few thousand miles before it's broken in but that wasn't the case with my brand new Altima when I got it in 2007. It had great mpg right away for the most part.
I'm keeping a log of my miles on the tank once the fuel light comes on so I can see if my miles per tank is improving with each fill-up. Last week the fuel light came on and my odometer showed 360 miles with 660 miles total on the car. I drive 70/30 city/highway and my 2002 Civic LX Couple gets around 300-310 miles once the light comes 50/50 city/highway (but I floor it a little more) on it and has a 13 gallon tank compared to the 18.5 gallon tank on the Optima. I drive the Optima like a grandma by the way.
What are your numbers? Please specify your city/highway breakdown and how many total miles you have on the car along with your car trim.