—Mike Ligon, Kent, Washington With cars such as coupes and sedans, you’re much better off with the windows down when doing errands around town. On the highway, drag becomes a factor, so the mileage cost of air conditioning is reduced, but not eliminated. And larger vehicles such as minivans and SUVs already have a lot of drag, so open windows are even less of an issue. You’ll get better mileage with the AC off.
