Air conditioning

[Tom B]

So just wandering, Does Driving with the air conditioning on lower MPG, and if it does, how much (roughly)

I can't understand why it would, obviously a tiny little bit of power would be needed to turn the AC Pump, but other than that? Are you really going to notice anything?

Tried looking on google but all the answers all contradict themselves.

cheers

 

[Anonymous]

I find it makes a noticable difference to the engine power. I think it pulls the engine down quite a bit, so I tend to only use it when I'm driving at a constant speed, then turn it off if I'm doing lots of starting/stopping.
How much it would effect the fuel consumption I don't know. Don't really use it that much!

 

[yippeekiay]

Depends on engine revs which equated to actual road speed basically, the higher they are the less difference in fuel consumption and vice versa.

In short - anywhere from 1% to 25%!!!! difference between having AC on or off.

EDIT:- Just had a quick google and found an article about Autoexpress doing a test for various things including air con which more or less backs up my thoughts.

http://www.autoexpress.co.uk/news/autoexpressnews/229776/the_mpg_mythbusters.html" onclick="window.open(this.href);return false;

 

[MikB23]

If I'm on the motorway I can feel a definite drop in power when I switch the AC on. You can physically feel the car drop off a little. As a rule if I'm on the motorway and want the AC on I drop my speed by 5-10 mph. Sounds daft I know but it will offset any loss in MPG.