I would beware of claims of those who have something to sell you such as a wind deflector when the only true evidence they state is ALL THE BIG RIGS USE THEM! In my travels I have visited with many RVers who claim they can't tell any difference at all.The flat surface of most big rig trailers make the wind deflectors more likely to work than on most RV,S that are rounded and more aerodynamic.I'm not saying you won't find someone who says it works for them but most I've talked to plan on getting rid of them when they get home.Same goes for vented tailgates .Tape a piece of string on the bed of your truck and with most modern trucks you will see that the tailgate collects at the most a minimum of air.