Flyboy speaks the truth! You are wrong, Route 66, oh so wrong, to use Mythbusters as a feeble attempt to make your point, lol.
Really though, the Mythbuster's episode has since been attacked relentlessly for many reasons. Off the top of my head:
1) They used two different vehicles to compete against one another!
2) Two different maintenance histories, no baseline!
3) Two different drivers, weight of vehicles, tires, wheels, etc
4) At what speeds? Yes, it is more fuel efficient to have your windows rolled up....above 55 mph. At that speed and above, you will lose mpg performance if your windows are down. But driving at 30mph, sure, it is better for mpg to enjoy the breeze.
They are entertainers and Hollywood types, not scientists, and not people who know how to conduct a proper test, apparently.
Not this time, Lee Harvey....