Dr Nick

Hi Everybody!

So its a bit hot and those of us (me included) who said aircon is a waste of money in the UK because you can just wind the window down, are probably feeling a bit sheepish...... til next week anyway.

Question is, can any of you say how having it switched on has affected your fuel economy?

And another question (no bulls**t - my mate dowm pub says type answers please): what if any effect does aircon have on your fuel economy, or anything else, when it is switched off. Presumaby there are still some extra wheels and pulleys spinning round even then, and the extra weight, and the difficulty gaining access to certain parts of the engine could increase service costs?

Cheers!

SJ_Skyline

Running the car with aircon switched on saps anywhere from 10bhp to 25bhp. Yes, it uses up more fuel.

Running the car with the AC switched off - god knows!


Wouldn't catch me without AC in this weather!

Krade

Running acar with aircon switched can be as bad as driving at 60 with the windows open, Ive been told It'll add between 3-5 miles mpg depending on how you drive.

Viper61

I've always been told that running around town having A/C on costs you on the MPG, but over 50-60 MPH your better off with the windows up & the A/C on, something to do with driving a parachute otherwise!

richrussell

As a test, I did a tank of fuel with and without aircon/windows open.

My average mpg with a/c off, windows shut is 25mpg (mix of 60/70mph roads and 20/30mph town)

Windows open full - 22mpg
A/C on, windows shut - 24mpg

Pretty conclusive to me that a/c saps less power than the drag caused by having the windows open.

This is climate control on a twin turbo Legacy GT-B btw, set to about 22C. Now I imagine on a non-turbo Impreza a/c would be more of an issue.

Rich.

Jza

Yeh - so you can save £0.50 a gallon and sweat to death... or keep it on

I'm sure the semi climate control on the new WRX's is more efficient anyway. I dont notice a reduction in performance!

Jza

DJ140

I went on a 300 mile motorway run this week and used aircon for every mile. The MPG was 28, cruising at 80-90 on the Autobahn, maybe 1 MGP less than normal.

Dan

Fat Boy Slim

A / C has little effect on the MPG if you are doing loads of motorway miles. get around 25, 26 mpg regardless of it on or off!!!!!

In this heat I could not live without it..............

John WRX

another thing to take into account is weight saving, ive saved 45 kg by removing mine.

Jza

John,

Not being funny.. but you'd rather go .25 of a sec quicker to 60 but BOIL in the hot weather????

Jza

John WRX

yeah, i work in temperatures of 300 degrees c every day so 35 in a car is nothing lol

Spoon

Why do people still think aircon = summer?

I use it in the winter too, it's great for clearing the windows and maintaining good visability.

The dial doesn't have to be at 20 after all.

Beemer_Deano

On the WRX the amazing demist setting has been invaluable - the windscreen mists up quicker and more often than any car I've ever had. AC now comes on in both demist settings on the WRX III instead of just one I noticed.

It may not be as cold as my old Audi, but it certainly has less effect on performance or economy - I can't say I notice any real difference in MPG.

Deano

Turboteeth

No fuel economy effect on my MY95 WRX - it's just it becomes jerky in traffic as the compressor cuts in and out all the time

richrussell

Turboteeth - You shouldn't notice any effect on the engine when the compressor switches in - bar the sound of the clutch engaging and the compressor spinning. The ECU should automatically raise the idle to compensate, so it's not noticeable.

Might be worth getting your aircon checked out, as it sounds like it may be presenting a higher load to the engine than it should.

Rich.

Scooby96

Even if it halved my full economy I'd still use it! Was a god send coming back from the beach yesterday