AC - Petrol Consumption ?

[VWKev]

When using your Air Con, how much more petrol is it actually using. I didnt think it used anything, but few people have said to me it uses quite a lot. I thought they were pulling my leg.

Is it true, and does it use much ?

[Wayne]

Running the a/c on my 5 series Bmw take around 4mpg off.

[Ben Lessani]

Can't remember the exact figure, but they were playing on Mythbusters, seeing the effect AC has on fuel economy.

Turns out its cheaper to drive with your windows down than with the AC on

[Mr Blue]

Im no expert but im guessing the aircon pump causes alot more drag for the engine which means more fuel.

Ive found that a few pumps spin more smoothly than others. (the mk4 eats air con pumps)

Might be worth getting those pumps checked out people.

[Wayne]

To be honest I have had 9 / 10 cars with air con and most were around 2mpg worse with it on, don't use mine a lot but run it once a week to keep it working.

[danny_p]

very much depends on the car, engine and aircon system tbh.    more modern cars suffer more arodynamicly  with the windows down than old ones also there ac is more efficent.

frend had a festa 1.2 or something and it had bloody good air con but turning it on had a massive effect on cars performance and economy, yet the v6 vectra i had  you chouldn't notice any diffrence in performance or economy 

[Agreeable Slick]

Larger the engine = less of an effect.

[bondbill2k2]

simply windows down 
Unless your trying to keep a sunday dinner frozen in the passanger footwell 

[dTEA]

simply windows down 
Unless your trying to keep a sunday dinner frozen in the passanger footwell 

why use the footwell when the glove box doubles as a fridge...saves melted chocolate in summer

[VWKev]

I honestly didnt think it would affect it at all, just show you how much i know.