Lifting gasses increase truck capacity

  We have a large number of trucks on the road that have wind diverters on the roof to make the aerodynamics of the truck better when pulling a tall trailer. Why not put a large balloon of a lifting gas (i.e. helium) in that empty space this would permanrntly be lifting up on the tractor reducing the weight but not the aerodynamics, therefore reducing the ammount of fuel required to move the load when moving uphill and reducing the load on the brakes when travelling downhill. This method would also be suitable for use in cranes and other lifting jobs.