Hot as heck last week, so AC on bust. And busting up my MPG hard. Last week I was at 50 for a tank (no AC), this current tank of 250 miles I'm at 46 and dropping! Seems to hurt it 4-5 mpg, unless I want to blame the new trailer hitch I put in last week (I don't). No, I don't use ECO mode Yes, I know AC hurts all cars' mileage! Question 1 How much does heavy AC use cut YOUR mileage? Question 2 Though the compressor is on in any case, how much better would mileage be using AC on low fan setting instead of high?