After reading tips for saving gas on this site, I’m wondering if I should remove the cross-bars of the roof rack on my Ford Explorer. The tip said a roof rack can cut gas mileage by 5%. I never use my roof rack. Should I start a campaign to get everyone to remove the cross bars on their SUV’s and save tons of gas nationwide? Seems like the little resistance caused by the roof rack would not make much of any difference.
That tip is one of those that belong in the dumpster IMHO.
No way is that rack responsible for a 5% fuel loss. The loss, if any, is so negligible as to be meaningless.
A lot of those tips are theoreticals tossed around by auto related articles in newspapers, magazines, and on those weekend auto shows on TV. Lot of theory and no basis.
(I actually forced myself to sit partially through one of those idiotic shows (twice) just to see what would be said.
It was on some DIY network or something. Totally off the wall comments about repairing electrics, completely false advice on repairing an A/C, and my personal favorite - installing a GM starter on a Ford Ranger truck. They need to watch their editing a bit.) 
I really don’t think it would make a noticable difference. I would not contemplate the idea.
This subject has been a popular internet and email rumor. But, usually such rumors get distorted and twisted. Go to http://www.fueleconomy.gov/feg/planning.shtml
and read that truth is your mileage will decrease an estimated 5% if you have a LOADED roof rack.