An Exercise in Fueltility?

Driven by the recent hikes in gas prices, a group of researchers conducted a series of experiments to determine when rolling down car windows trumps the AC in terms of fuel efficiency.

Their findings? On the highway, closed windows decrease air resistance, so run the air conditioner. But in stop-and-go traffic, shutting off the air conditioning and opening the windows can lighten your fuel use. Air conditioning can lower your fuel economy by 10 percent to 20 percent.