I think my cummins might be. Lemon. Towing about 6k up to barnwell mountain I only got 12mpg and without a load I am getting 17. 2006 auto
Mine gets 17 unloaded freeway at about 70mph. thats with bald tires. most people i talk to average about that too. when i bought the truck it said it was getting 24mpg and hand calculated was 15mpg with it on crazy larry mode. gets a couple miles better with it on performance.
