Bit of a genralisation here. Turn off the auto air conditioning (RED LIGHTON) Set the temp on manual to whatever your happy with and set the fan to one or two dots. Now set your position buttons (windscreen, middle, feet) to where ever suits. Now watch your MPG go up. Leaving the air con on is a sure fire way of decreasingyour MPG. It is wise however to run it once in a while.