Originally Posted by cpaharley2008
I was shopping today for a new SUV and drove a Nissan Xterra with a factory tubular roof rack. The salesman then showed me on the "S" model an additional gear compartment built in the front of the roof rack. To open there is a catch and a compartment door flips up. There are 2 pistons on each side like on your hood keeping it open. It immediately reminded me of those air dams on tractor trailers. I know the subject has been discussed there are manufacturers of bolt ons. I asked the salesman if it could be left open, he asked me why and then the light
went off, "Oh, yes, you want to tow and this would deflect the air" and we both smiled.
Anyone else seen this option in action?
I have a Freestar minivan and wanted to try deflecting the air over our 16.5 Aerolite stick built trailer. We went to Texas last winter without the air dam(12.3 MPG), and again this year with a homemade air dam(15.4 MPG).Needless to say I was impressed. I couldn't find a commercial product made for minivans so I constructed one from used waterproof concrete forming plywood($10) sold locally. With a bit of hardware to fasten it to roof racks and some paint($25 in all) we were ready to go. I figured if it didn't work it could be discarded when we got far enough south to get warm weather so I didn't freeze my fingers removing it. A flat plate that is narrower than the trailer obviously won't clear the outside corners so I added end plates that start about 10" in and taper out to the end of the main board which tilts up about 30 deg. I drew a scale model on CAD to figure out what would work but you could use string between the tug and trailer to calculate angles.The trailer definitely tows easier so there could be the temptation to drive faster but then you lose most of the gain.