During the hot summer months, leaving the windows rolled up (while running the air conditioner inside) is a more fuel-efficient way to drive at highway speeds. Open windows create drag, which reduces the aerodynamic flow of your car. “But it’s summer!” you may say. If you like to have your windows down, at least do this: Leave your sunroof closed. Not only does an open sunroof bring in the lowest amount of airflow, it also creates the highest drag. Cracking the door windows is the next best thing.
ANDREWS MCMEEL SYNDICATION