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DCL

Go on any highway and you'll see many vehicles with roof racks. Some are actually carrying things (bikes, kayaks, etc), but the vast majority are empty, and a good subset of those will never actually carry anything.

We know that aerodynamics matters a lot at highway speeds (the more 'slippery' your vehicle is through the air, the less your engine has to work to keep the vehicle moving), but what kind of impact does a roof rack have on MPG? That's the question that Darin at MetroMPG asked himself, and he conducted an experiment to find out.