I towed a tag trailer 450 km down the highway at 55-60 mph and got 37 liters/100 km. (6.4 mpg). Can you get a Dodge or GM to go through that much fuel?
I actually never considered what the law would say about transporting a piece of equipment like this down the highway. I suppose you're right... probably what I did wasn't legal. It could be moving it with a tractor would have been legal....Likely much more dangerous but legal.