I am pretty sure my brother's 2014 that I posted for sale here was getting 18-21 unladen. I know he was shocked at how good the mileage was for such a beast of a truck.
He ended up selling to a dealer.
He is out of the Country right now, but will check when he gets back.
Was listed for sale here:
https://www.yenko.net/forum/showthread.php?t=169188