Most freight-hauling trucks that I see on the roads have a top faring, presumably for better aerodynamics. The truck that I drive is a Volvo flat-top, and given the weights that I pull, it's debatable whether any such faring would make a difference ( not to mention the fact that since I haul dry bulk, I need to go to some very cramped spaces where a top faring would easily get torn off ). The question that comes to mind, therefore, is how much of an impact does the top faring have on fuel consumption ?

 

When I added the wing to the top of my 379 Pete, I saw an instant 3/4 mpg increase. I would assume that a fairing would be similar.

 

I think alot of it also has to do with what you pull. Tanks don't really come that far above the truck. So if you had a wing i think it would be kinda useless. Vans are a diff. story cuz the stick up 1-2 ft above a flattop truck or daycab. That was the nice thing when i ran tankers i was 12' so i could fit under alot of bridges that vans wouldn't have.

 

They also catch dirt big time and make your truck a nightmare to get clean, and if you run in the fluffly kind of snow either, they sometimes fill with snow.