[Snax]

Modern AC is certainly more efficient than it used to be, but to put it in perspective, my i3 can use up to 2.5kW at full AC load. In my car this works out to additional drag close to driving at 25 mph - or about 16% of total drag at 65 mph.

I open the windows when I can around town, but at highway speeds I don't think I am giving up much with the AC on particularly since it is rarely needed at 100%.