My 2010 with the 6.0 and 6 speed got at best one time 13 mpg around town. Most of the time it was about 12.5. My 2024 6.6 10 speed is getting almost 13 around town and it is not even close to broke in yet. I think it will be close to 14 after it is broke in. The truck also is about 1300 lbs heavier.