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air con / fuel economy


I noticed many a concern about fuel economy in the posts of this forum and so have kept an eye on it too since my 6 days of ownership.

I reset the trip computer a couple of days ago and after about 30 miles noticed the consumption was 28.5 mpg.

Today I had a round trip of 40 miles to do and so reset the trip again and switched off the air con. Average was at 37 mpg afterwards.

Only very early days yet, and the two different averages were from different drives.

But might be worth turning off the air con in these cold conditions.

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Very easy to get two very different averages from such short drives.

The A/C will not account for that difference.
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Out of interest what difference does it make? I know people keep theirs on all the time, so it cant be that much? I cant keep mine on all the time, it makes my face dry and sore however keeping it off for too long especially over the winter, causes it to go smelly. (the aircon, not my face).
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I've heard in the past it [the air con compressor] can increase fuel consumption by between 2 and 5% across various different car maunufacturers. Old addage: "you don't get summat for nowt".

Whilst on the subject of minor mpg effects watch out for cruise control. In my experience driving on cruise at constant speed with varying fuel input is more "costly" in mpg terms than driving at a constant throttle position and allowing the engine to find the optimum speed based on the available torque and road conditions ie. inclines etc.

Something to consider - even though don't understand the link between driving an Alfa and using cruise control!
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oh and I forget: if you are going to switch off air con for a while it's best to run it once a week to keep the seals "wet" and operative; as well as clear out the smells and possible mustiness. Difficult to get system to fully operate in these cold conditions however.
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Surely in these current cold conditions the AC won't be doing anything, leaving it on will just make it available if it's ever needed to cool incoming air.

P.S. Mine is always on and my consumption is shocking.

P.P.S. The best way I find to improve fuel consumption in my Alfa is to drive my wife's Megane.
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You will find that that air con compressor is turned off automatically when the temp goes below around 3c, even though the light stays on. If you turn the aircon off, and it is below 3c you will find that you can't actually turn it back on.

From what I have read, when you are cruising on the motorway, the compressor hardly affects the fuel consumption and is better than opening the windows, but around town where you have a lot of stop/start traffic its best to turn the aircon off and open the windows.
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air , con , economy , fuel

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