My gas mileage for the last week was 29.5 mpg. I expected it to be only about 27 mpg, but there is a section of I-88 that is normally 70 mph, but because of construction it is being heavily enforced to 45 mph. I didn't think I would see a noticeable difference in gas mileage traveling at slower speeds for just several miles each day, but I guess I was wrong. That makes me think how much oil we could save if the national speed limit were reduced to 55 mph again.