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:eek: Living in Savannah requires that I use AC in hot weather, and I am disappointed in the reduction in my MPG while I use the AC. I was getting 55 MPG when I did not use AC, and this was commuting to work in small city driving. Using AC I am currently getting 43 MPG. I am surprised that the AC takes that much gas to run. I should not get too pouty, because it is still more than most other cars get, but I got really used to filling the tank every 6 weeks. Other wise, I love the zippy handling and "efficient" braking, and I would get another in a heartbeat if anything happens to the one I have...
blue moon pearl, 2003
 

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The problem is that the AC compressor runs off the engine's accessory belt, so the engine has to be running whenever the AC decides it needs to be colder. (Leave the MAX button off, and set the knob to AUTO to minimize this.) So, a lot of times when the car would normally be in stealth mode (which is what gives such great city mileage), the engine has to run anyway.

You can try to override this manually by turning off the A/C button everytime your car would normally be in stealth during your commute (stopped, coasting, cruising on level or downhill roads), and then turn it back on whenever the engine would normally be on (starting out, accelerating). Of course, this is a very manual process.

Or, you can trade your 2003 for a 2004 when they come out. The 2004s have an electric AC compressor that doesn't require the engine to be on.

Does anyone know of any other (less manual) ways to minimize AC usage of the engine?

Douglas (2002 Silver, Wisconsin)
 

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Not always a good idea : wide open windows create drag, especially at high speed, and this solution can be worse. Try using the recycling position sometimes instead ; the AC will have less work to do. I manage to get around 50 MPG with AC on while cruising on relatively flat roads and with an outside temperature of 30C (86F). But AC is really an MPG killer if you want to refresh the car for short trips, if the car is already hot after being exposed to the sun.
 

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If you leave the temp setting on the lowest, the engine will have to run more to keep the A/C on. If you set it for a temp that you can live with, but not too cold, the A/C will stay off more and the engine will run less. I know it is easy to start up on a hot day and turn the temp way down, but if you can remember to turn it back up after you get comfortable, you will burn less fuel.
 

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AC kills mileage

My experience in Phoenix is similar. Was getting about 49mpg without AC. Now getting about 43 in the summer. Here, the afternoon highs are routinely above 110 degrees. I keep the AC set to AUTO and RECIRC, and keep the temperature setting as high as is comfortable. I can hear the engine go off at stops, and I can feel the air temperature increase somewhat. If I sit long enough, the engine starts again to bring the temperature back down. So, the higher the temp setting, the more time the engine gets to stay off.

I play with the temp setting as I go along. I usually start it out low to get max initial cooling (with RECIRC off if the car's been sitting in the sun). And when I think that the engine won't be off much anyway, I lower it. Then when I think that I'll be stopped a lot, I raise the temp a bit.

I sure wish I'd found out about the electric-AC feature on the 2004 sooner!

--Barry
 

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AC and MPG

Another trick I use that makes a big difference in city driving is to turn the AC off at red lights. It takes a couple of minutes before the air warms uncomfortably and by then the light has changed and with guys behind me anxious to go I have to accelerate enough that the engine kicks on anyway. It is depressing to watch the mileage decline as you SIT there, and turning the AC off helps keep that from happening.
 
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