I currently drive a 2000 Grand Prix GTP, my commute is 8 miles highway then 3 city every day. Sometimes that highway mileage ends up being bumper to bumper but more often than not it isn't. I also tend to have to drive around for work once or twice a week, where I am going changes each time so it is unpredictable. Also, once a month I have a 220 mile round trip drive which is about 95% highway. I get about 22 mpg on the 11 mile commute and about 28 on the highway commute. I tend to keep it around 50-60 mph whenever possible and was hoping to pick up some tips to pick up some better mileage. About my car - It has a 3.8 liter supercharged 6 cylinder with a 4 speed (OD) automatic tranmission. EPA estimates are 19/28 I believe.