@nprofile1q... @nprofile1q... Vehicle fuel use (very simplified):
(weight of vehicle + weight of load) x some factor = fuel use.
If you are loading a truck you are loading it with stuff you want to use.
If your car has a boot full of sh*t you might need one day but have kinda forgotten about you are moving it for no purpose.
So they are tehnically making sense but they are ignoring the other things mentioned here. Road damage being the primary one.
greater axle weight (I think) exponentially increases road damage.