Ya around there, my best was 13L per 100   it gets cut in half at a minimum when towing heavy, but man does it ever tow nice!

I had one of the 1500HDs years ago with a 6.0L and it was absolutely brutal on fuel.     I bet 18L/100kms empty would be very optimistic.       

Never been a dodge guy, but I think they are onto something with this new ramcharger hybrid.   https://www.ramtruck.ca/en/ramcharger   Makes sense.  You loose the tranny and the transfer case.  Replace it with electric motors and a generator.  Kinda the best of both worlds.  You get an ev for daily driving.  Will still get you up north on a 6 - 8 hr haul without ridiculous charging stops.  Should be decent for towing capability.  Be interesting to see some reviews.

Technology is changing fast.   batteries in construction equipment have increased in charge capacity by 30-40% over last 5-6 years. Super Fast charging batteries and Super fast chargers that are capable of charging from a small on board generator.   i have seen a 100t crawler crane that has this system.  The batteries can run for 45mins on their own.   smaller onboard diesel generator burns less then half the diesel the standard crane would burn.   Or this crane can be plugged into electrical grid and run off electricity.   Hydrogen engines being introduced in construction equipment.

What would you get empty driving down the highway. 14 ish L per 100?