The magnetic or vacuum attached racks are one option that seems to work well. I have a Yakima rack and, for years, have used the cross-****ry ski rack to carry my set up rods during the day. There have been two or three times when I have had to take the rods down because of heavy cross winds, but then, it wasn't much use trying to cast or fish under those conditions. If you have a Yakima rack, or similar, the ski rack is not too expensive.
I use short bungie cords that are about 6-8 inches long, ends connected with a small 'ball.' Put some padding on the cross bars (front only if you put your reels in covers) apply the bungie cords and your good to go (up to 70mph). Point the rods straight ahead and your good to go.
Only place you need to pay attention is passing very large trucks due to the wind they push off to the aside. Here you 'punch it' and get by same.
Been using these (introduced to them by JD Jones) for a couple of years and they work great. Cost? 89 cents each.
A forum community dedicated to Spey casting, fishing, flies, and enthusiasts. Come join the discussion about trails, licenses, fishing, game laws, styles, reviews, optics, accessories, classifieds, and more!