Effect of A/C on MPG

Mike24 · 5th August 2015, 20:28

I have always tended to keep the A/C on auto, partly out of habit, and partly because cool air helps keep me awake on long journeys. However, I would be interested to know how much difference it makes to mpg to have the A/C on Econ rather than Auto.

Heddy · 5th August 2015, 20:37

Always believed the effect on mpg was negligible, it's not that much of a strain to drive an air con pump/compressor. I've no figures but await further replies.

roverbarmy · 5th August 2015, 20:41

Cheaper than driving with your windows down and ruining the aerodynamics!

MrDoodles · 5th August 2015, 20:50

Although I run Ed's ATC 24/7 365, pretty sure they did this Mythbusters a few years ago and below 40 mph, turning off the air con and opening the windows was more economical and above 40 mpg, closing the windows and running the air con was better?

Ps3000 · 5th August 2015, 21:09

I couldn't get a difference of even 1mpg on the fuel computer when I tried to test it using the same regular run.

Not sure what that proves - not much really.

Vossy · 5th August 2015, 21:20

Well the difference is letting wasps in or being cool 😀

Dragrad · 5th August 2015, 23:02

This might be of interest......

http://www.autoexpress.co.uk/car-new...pg-mythbusters

stevenicks · 6th August 2015, 06:34

The way Look at it is that hot summer days appear now to be far and few between but when it is hot and I am on a short or long journey I like to travel in comfort with the air con blasting aware. Forget the expense (which would be minimal anyway) and live the dream.
Alternativley in a winter when it is cold I like nothing better than warming the car up for a short time and plonking my rear end into a nice warm, heated seat.... Bliss.

Mike24 · 6th August 2015, 07:03

I agree; whilst I appreciate the fuel economy of my car, a large part of my reason for buying it was the comfort it affords during long journeys. It would be a shame to become so preoccupied with frugality that the luxury of our cars is not fully enjoyed.

SD1too · 6th August 2015, 11:50

Quote:

Originally Posted by Ps3000

I couldn't get a difference of even 1mpg on the fuel computer when I tried to test it using the same regular run.

Not sure what that proves ...

It proves that, if there is a difference, it's too small to measure and therefore insignificant.

Simon

5th August 2015, 20:28	#1
Mike24 Loves to post Rover 75 CDTI Auto Saloon Connoisseur SE Join Date: Apr 2015 Location: Coventry Posts: 358 Thanks: 166 Thanked 67 Times in 56 Posts	Effect of A/C on MPG I have always tended to keep the A/C on auto, partly out of habit, and partly because cool air helps keep me awake on long journeys. However, I would be interested to know how much difference it makes to mpg to have the A/C on Econ rather than Auto.

5th August 2015, 20:41	#3
roverbarmy This is my second home Roverless + 1.7D Sportage Join Date: Aug 2014 Location: East Norfolk Posts: 7,086 Thanks: 729 Thanked 2,021 Times in 1,449 Posts	Cheaper than driving with your windows down and ruining the aerodynamics! __________________ Oil in my veins!

5th August 2015, 23:02	#7
Dragrad This is my second home *None DROWNED** Join Date: Aug 2007 Location: Cardigan Posts: 33,339 Thanks: 1,257 Thanked 1,664 Times in 1,081 Posts	This might be of interest...... http://www.autoexpress.co.uk/car-new...pg-mythbusters __________________ Andrew Ich Dien Problem solving is... lateral thinking SEARCH FIRST ...ASK LATER...

5th August 2015, 20:37	#2
Heddy This is my second home None Join Date: Feb 2013 Location: None Posts: 5,556 Thanks: 465 Thanked 1,161 Times in 924 Posts	Always believed the effect on mpg was negligible, it's not that much of a strain to drive an air con pump/compressor. I've no figures but await further replies.

5th August 2015, 20:50	#4
MrDoodles Banned MG ZT+ V6 190 Join Date: Nov 2011 Location: Spalding Posts: 13,245 Thanks: 369 Thanked 1,196 Times in 818 Posts	Although I run Ed's ATC 24/7 365, pretty sure they did this Mythbusters a few years ago and below 40 mph, turning off the air con and opening the windows was more economical and above 40 mpg, closing the windows and running the air con was better?

5th August 2015, 21:09	#5
Ps3000 Gets stuck in None at moment Join Date: May 2013 Location: Loughborough Posts: 899 Thanks: 230 Thanked 125 Times in 113 Posts	I couldn't get a difference of even 1mpg on the fuel computer when I tried to test it using the same regular run. Not sure what that proves - not much really.

5th August 2015, 21:20	#6
Vossy Why? ... MG ZT+ Cdti Auto saloon. Join Date: Jul 2014 Location: Blockeswich, South Staffs Posts: 1,555 Thanks: 173 Thanked 483 Times in 330 Posts	Well the difference is letting wasps in or being cool 😀

6th August 2015, 06:34	#8
stevenicks This is my second home MG ZT 180 Auto / Rover 75 2.0 Diesel Join Date: Apr 2013 Location: Brecon. Posts: 7,465 Thanks: 3,297 Thanked 1,666 Times in 1,264 Posts	The way Look at it is that hot summer days appear now to be far and few between but when it is hot and I am on a short or long journey I like to travel in comfort with the air con blasting aware. Forget the expense (which would be minimal anyway) and live the dream. Alternativley in a winter when it is cold I like nothing better than warming the car up for a short time and plonking my rear end into a nice warm, heated seat.... Bliss.

6th August 2015, 07:03	#9
Mike24 Loves to post Rover 75 CDTI Auto Saloon Connoisseur SE Join Date: Apr 2015 Location: Coventry Posts: 358 Thanks: 166 Thanked 67 Times in 56 Posts	I agree; whilst I appreciate the fuel economy of my car, a large part of my reason for buying it was the comfort it affords during long journeys. It would be a shame to become so preoccupied with frugality that the luxury of our cars is not fully enjoyed.