Fuel Saving Tips
Unless you have two compressors, using the rear a/c along with the front a/c will not affect your mileage. Either way the compressor is running. It turns at one resistance, either on or off. (there are thermodynamic resistance differences with more refrigerant v.s. less but we don't need to get that detailed). If you are driving a minivan and you get 20 with the A/C on and 22 with it off are you going to sweat for a 10% gain? Perhaps you need to reconsider your vehicle if you can't afford 20 mpg and are trying to get two more yet sweat like a pig.
posted by jspahn on June 15, 2012
this tip works for 68% of voting Fuelly members.