I made 6-connective weekend trips to a neighboring city. I came across many 18-wheelers on the interstate highways. Some were old, boxy Peterbilts, some were very aerodynamic looking Freightliners and Volvos. Regardless of the boxy cabs, or aerodynamic cabs, they all have some kinds of "add-on" to improve the aerodynamic of overall setup. Without out a doubt, the raised wind deflector over the trailer was every one I have came across.
Another interesting observation about the trucks - there are only a few brands of truck cab integrators:
Freightliner
Volvo
Peterbilt
Kenworth
International
Ford
Mack
Further more - Detroit Diesel, Cummins are popular engine choices for truck manufactures that don't have their own branded engines.
