It is imperative that you stay in the slow lane and never leave it.Instead leave early and drive slower.
Your gas mileage is horrible at 200 miles per 12 gallons of gas your mpg is 16.67 miles a gallon.
here is a quick link to a site to figure your mpg with-
http://ecomodder.com/forum/showthread.php/how-calculate-mpg-fuel-economy-formula-352.html