Chops

You will find there is a toggle switch to the right of the steering column labeled "ECT" with "Power" being the top option and "Snow" being the bottom option. As for a more detailed explanation of what this switch does I'll leave it to the pros on here to explain it as I'm pretty new too.

I have almost 60,000 miles on my IS350 and I average around 22 per gallon with just city driving. One tank I was in a hurry nearly every day and only averaged 17.8 per gallon on that tank. With just interstate I get closer to 26-27 gallons.