Speaking of this problem, I think my IS350 MPG is really bad too. I started to pay close attention to my average MPG on the system and it reads less then 18. Also, my range approximator only gives me around 300 at most 320 and that is about how many miles I get (I know this varies but thats about what I get in real miles). I made some calculations myself and if the tank is 17 gallons (if im not wrong) it should show and give a total of 357miles(21*17 this is calculating with city mpg only) for a full tank. I only get around 300 combined with city and freeway.. That is really bad now when I think about it... Tell me what you guys get for total, maybe I am over thinking.