Drive a 2012 freightliner hauling sand. dd15 3.55 rear end. Usually close to 80,000lbs but even when im not loaded, the truck tends to burn a lot of fuel. averaging about 5 miles to the gallon. Oilfield driving tends to have a lot of starts and stops through small towns but even when my trips consist of coasting for a bit the truck doesnt do well. Changed out several fuel filters and def filter. changed oil. I try to stay progressive changing gears, yet I'm thinking it can be improved but don't know how. Wondering if I'm too heavy with the truck having too much stuff inside the cab or something.