I am retired and we just yesterday finished a trip to Great falls ,MT from southern Indiana. Fuel prices ranged from $4.00 to $3.75. I have a '04.5 Dodge 2500 Quadcab with a 5.9L Cummins diesel and 3.73 rear end. I run at 65mph with an rpm of 1800 which seams to be just right. Most interstate speed limits were 65 to 70 with a few miles at 75. My average mpg was 11+. We are right at 19k to 19.5k gvw. My biggest problem with traffic was the 18 wheelers who wanted to pass me, but would take a mile to do it and then pull back in front of me with very little space between us just so they could let the traffic behind them pass. I had a FED driver do this to me on I-94. Very much not professional in my eyes. JME.