What is a good roof-rack configuration for optimal gas mileage? I have a standard 2 bar roof rack (such as Yakima or Thule) with interchangeable and move-able bike / ski racks. I often carry 2 bicycles. Which will give me the best (least worse) gas mileage on my car:


Both bikes as close together as possible, or on opposite edges of the roof?
If together, centered, or on one side or the other?
Front wheel on (full upright) or front wheel off (fork mount)?
From my experience frequently carrying bikes, skis, roof boxes, and even 55 gallon drums on my roof rack, I've found that they pretty much all give a hit to the gas mileage, but the configuration doesn't really matter as long as you don't do anything ridiculous.

However, a fairing helps cut down on noise tremendously.