True cost of using A/C while driving

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My fueling policy in my car is to fill up then drive until the low fuel light comes on then fill up again. Now I have been doing this for some time and normally make a mental note of the trip mileage before I reset after filling. No calculations or recording just a mental note of how many miles I tend to do each week. I filled up this morning as my fuel light had just activated.
Now this week has been absolutely roasting as it is this morning with temperatures well into the 30Cs, consequently my A/C has been working full bore every day this week even when parked if needed.
This is obviously going to have an effect on my MPG so I thought I would share with you just how much it costs to use your A/C.
Nothing scientific but I had done 25% less miles this week on a tank full when my fuel light came on.
Conclusion........Using A/C could cost you 25% more on your fuel bill.
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buttons said:
My fueling policy in my car is to fill up then drive until the low fuel light comes on then fill up again. Now I have been doing this for some time and normally make a mental note of the trip mileage before I reset after filling. No calculations or recording just a mental note of how many miles I tend to do each week. I filled up this morning as my fuel light had just activated.
Now this week has been absolutely roasting as it is this morning with temperatures well into the 30Cs, consequently my A/C has been working full bore every day this week even when parked if needed.
This is obviously going to have an effect on my MPG so I thought I would share with you just how much it costs to use your A/C.
Nothing scientific but I had done 25% less miles this week on a tank full when my fuel light came on.
Conclusion........Using A/C could cost you 25% more on your fuel bill. View attachment 415013
Click to expand...
More likely to be the extra fuel used idling when stationary.
I use the aircon a lot throughout the year and still average 32 mpg on my 120 Ducato PVC
 
Figaro said:
I'd be very suprised if that was anything like accurate.
My experience is it makes little difference and for the comfort it provides its well worthwhile
Click to expand...
Climate control is there to use Figaro and use i do but there is a cost penalty and my trip recorder records very similar numbers each week. This morning it recorded 25% less when I filled up. Turning the fan and an on load compressor is not for free it will drag your MPG down.
 
AFAIK the pump uses about 5 horsepower. At tickover that's a a large chunk out of the engine power so fuel consumption will be relatively heavy. In my car it is on by default, but it does have 258 HP available when it gets going so it's not so much of a problem.:cool:
John

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matamoros said:
More likely to be the extra fuel used idling when stationary.
I use the aircon a lot throughout the year and still average 32 mpg on my 120 Ducato PVC
Click to expand...
Where is the comparison of the A/C not being on. Your van may well do 38 without the a/c on (y)
 
buttons said:
My fueling policy in my car is to fill up then drive until the low fuel light comes on then fill up again. Now I have been doing this for some time and normally make a mental note of the trip mileage before I reset after filling. No calculations or recording just a mental note of how many miles I tend to do each week. I filled up this morning as my fuel light had just activated.
Now this week has been absolutely roasting as it is this morning with temperatures well into the 30Cs, consequently my A/C has been working full bore every day this week even when parked if needed.
This is obviously going to have an effect on my MPG so I thought I would share with you just how much it costs to use your A/C.
Nothing scientific but I had done 25% less miles this week on a tank full when my fuel light came on.
Conclusion........Using A/C could cost you 25% more on your fuel bill. View attachment 415013
Click to expand...

Have you consdered swapping your gas guzzler for an EV or maybe a hybrid?

Our new hybrid car runs the AC system off the big Lithium battery and uses no petrol for this function when stationary. It uses a KERs system for braking and charging the battery; very clever. Finally, some F1 tech has trickled down!

Like matamoros our Ducato PVC returns similar diesel consumption figures with cab AC on permanently. No worries. :cool:
 
Many years ago here in must have air con Spain we had a Ford Ka as a run about.
When I put the air con on I had to change down gear....however our 3 litre Renault powered MH is never bothered...I also haven't noticed any difference in fuel consumption....but at less than 1€ a litre why bother..... interesting topic though...
 
buttons said:
My fueling policy in my car is to fill up then drive until the low fuel light comes on then fill up again. Now I have been doing this for some time and normally make a mental note of the trip mileage before I reset after filling. No calculations or recording just a mental note of how many miles I tend to do each week. I filled up this morning as my fuel light had just activated.
Now this week has been absolutely roasting as it is this morning with temperatures well into the 30Cs, consequently my A/C has been working full bore every day this week even when parked if needed.
This is obviously going to have an effect on my MPG so I thought I would share with you just how much it costs to use your A/C.
Nothing scientific but I had done 25% less miles this week on a tank full when my fuel light came on.
Conclusion........Using A/C could cost you 25% more on your fuel bill. View attachment 415013
Click to expand...
Negligible for the comfort it gives. As matamoros says do you normally leave engine running when parked even with A/C off???
My A/C never gets turned off.
 
buttons said:
My fueling policy in my car is to fill up then drive until the low fuel light comes on then fill up again. Now I have been doing this for some time and normally make a mental note of the trip mileage before I reset after filling. No calculations or recording just a mental note of how many miles I tend to do each week. I filled up this morning as my fuel light had just activated.
Now this week has been absolutely roasting as it is this morning with temperatures well into the 30Cs, consequently my A/C has been working full bore every day this week even when parked if needed.
This is obviously going to have an effect on my MPG so I thought I would share with you just how much it costs to use your A/C.
Nothing scientific but I had done 25% less miles this week on a tank full when my fuel light came on.
Conclusion........Using A/C could cost you 25% more on your fuel bill. View attachment 415013
Click to expand...
You dont get owt for nowt,,,BUSBY.

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SpeedyDux said:
Have you consdered swapping your gas guzzler for an EV or maybe a hybrid?

Our new hybrid car runs the AC system off the big Lithium battery and uses no petrol for this function when stationary. It uses a KERs system for braking and charging the battery; very clever. Finally, some F1 tech has trickled down!

Like matamoros our Ducato PVC returns similar diesel consumption figures with cab AC on permanently. No worries. :cool:
Click to expand...
As you are aware SD nothing is for nothing, we can do things more efficiently but even charging you battery on your hybrid is costing you at the pump.
Yes I have been looking at hybrids and EVs but nothing yet has attracted me enough to change over.
 
My car is normally running at 32mpg on a run
Have noticed if I turn off the climate control it will add another 1-2 mpg
Not a big difference.
I can also put it in Eco mode that will turn off a non essential bits like the active air suspension, doesn’t seem to make much difference in this mode again only 1-2 mpg.
 
SpeedyDux said:
Have you consdered swapping your gas guzzler for an EV or maybe a hybrid?

Our new hybrid car runs the AC system off the big Lithium battery and uses no petrol for this function when stationary. It uses a KERs system for braking and charging the battery; very clever. Finally, some F1 tech has trickled down!

Like matamoros our Ducato PVC returns similar diesel consumption figures with cab AC on permanently. No worries. :cool:
Click to expand...

Your hybrid doesn't have a perpetual motion engine. Just because it comes out of your battery right now, doesn't mean it won't eventually come out of your petrol (or possibly electric hookup if a PHEV) when the battery needs to be recharged.
 
buttons said:
As you are aware SD nothing is for nothing, we can do things more efficiently but even charging you battery on your hybrid is costing you at the pump.
Yes I have been looking at hybrids and EVs but nothing yet has attracted me enough to change over.
Click to expand...

You're the one complaining about how much the AC system is costing you at the pumps! I'm expecting the incremental extra cost of AC at the pumps of our hybrid will be scarcely noticeable, unlike your 25%. :LOL:
 
poppycamper said:
Negligible for the comfort it gives. As matamoros says do you normally leave engine running when parked even with A/C off???
My A/C never gets turned off.
Click to expand...
This is moving away from my OP which highlighted the additional cost of using a/c not if we should be using it or not. Leaving your motor running when stationary is part and parcel of using a/c it is to keep you cool.
Leave your a/c on throughout the year doesn't mean the compressor is working very hard during the winter.

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SpeedyDux said:
You're the one complaining about how much the AC system is costing you at the pumps! I'm expecting the incremental extra cost of AC at the pumps of our hybrid will be scarcely noticeable, unlike your 25%. :LOL:
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My air con is free,,,i either open the windows but mainly walk...Same on van,,i open the windows,,BUSBY(y)(y):LOL:
 
Try repeating the same trips with the aircon off and windows fully down for a comparison. Of course there is a price to pay whenever energy is used either by running a compressor or additional drag, but you can sit and roast or choose options that will be more comfortable but that will both have an effect on fuel consumption.
 
SpeedyDux said:
You're the one complaining about how much the AC system is costing you at the pumps! I'm expecting the incremental extra cost of AC at the pumps of our hybrid will be scarcely noticeable, unlike your 25%. :LOL:
Click to expand...
Im not a complainer SD least of all about the cost of running my A/C. My post was just to highlight the fact that running A/C could cost you an extra 25% at the pumps. Followed by the Yorkshire war cry. :coffee:
 
Deneb said:
Try repeating the same trips with the aircon off and windows fully down for a comparison. Of course there is a price to pay whenever energy is used either by running a compressor or additional drag, but you can sit and roast or choose options that will be more comfortable but that will both have an effect on fuel consumption.
Click to expand...
I cant choose as there is no air con on van..Have it on car but never use it..Nothing to do with cost just dont like it,,BUSBY.

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buttons said:
Im not a complainer SD least of all about the cost of running my A/C. My post was just to highlight the fact that running A/C could cost you an extra 25% at the pumps. Followed by the Yorkshire war cry. :coffee:
Click to expand...
Only if you sit in it,when stationary,with the engine running and the aircon on. Otherwise it probably increases your consumption by 1% to 5% depending on the car.
 
buttons said:
Where is the comparison of the A/C not being on. Your van may well do 38 without the a/c on (y)
Click to expand...
Far more likely to be the idling or around town use to lower the mpg.
Mines on 11 months of the year here usually but it is the around town gear changing that reduces the consumption. worst is 28 & better is 33. On the autovia it averages 38-40 with a&c on.

It is more than likkley the idling & around town dawdling dragging mpg down
 
I feel that I should add......I have absolutely no idea how many miles per gallon my car returns either with or without the A/C on but it does record less trip miles with it on.:cool:
 
This post is funny!
The title sounds very ominous, "The TRUE cost" of running air con. I thought there would be all sots of links for research done by Shell or BP along with some links and real world testing. Instead some bloke thinks he uses up to 25% more fuel because he made a note of it in his head. buttons I applaud you for this post.
PS I have also done some research and I have made a note that if I use a cash point, it costs me money as I have less money in there than when I started!
 
cmcardle75 said:
Your hybrid doesn't have a perpetual motion engine. Just because it comes out of your battery right now, doesn't mean it won't eventually come out of your petrol (or possibly electric hookup if a PHEV) when the battery needs to be recharged.
Click to expand...

I accept that. It is a self-charging EV hybrid. The big gains in fuel economy come from the Atkinson cycle petrol engine that is optimised to approx 40% thermal efficiency when recharging the Lithium battery, plus the generator recovering kinetic energy during braking. The auto gearbox selector has a "brake" setting that maximises this recovery. I'm still trying out these clever options. On a long steep hill (12%) that I drive regularly in the previous car (and the Ducato) it was necessary to use cadence braking and change to a low gear to keep the speed down to about 50 mph. In the hybrid on the same hill using the brake setting it slowed to about 37 mph without using the footbrake. Impressive. I had to use the throttle pedal to speed up again and avoid impeding cars behind. By the time we reached the bottom the Lithium battery was showing 100% charged, up from 50% at the top of the hill. Conventional cars throw away all the kinetic energy via braking.

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Park in the shade and switch engine off.
You will always find a crowd of people there who have spent time abroad. They also walk down the street in the shade rather than in the sun.
 
SpeedyDux said:
I accept that. It is a self-charging EV hybrid. The big gains in fuel economy come from the Atkinson cycle petrol engine that is optimised to approx 40% thermal efficiency when recharging the Lithium battery, plus the generator recovering kinetic energy during braking. The auto gearbox selector has a "brake" setting that maximises this recovery. I'm still trying out these clever options. On a long steep hill (12%) that I drive regularly in the previous car (and the Ducato) it was necessary to use cadence braking and change to a low gear to keep the speed down to about 50 mph. In the hybrid on the same hill using the brake setting it slowed to about 37 mph without using the footbrake. Impressive. I had to use the throttle pedal to speed up again and avoid impeding cars behind. By the time we reached the bottom the Lithium battery was showing 100% charged, up from 50% at the top of the hill. Conventional cars throw away all the kinetic energy via braking.
Click to expand...
Sounds a nightmare if things go wrong,,,BUSBY :LOL: :LOL:
 
Ive been working in automotive A/C since the 80's

Modern systems use very little extra fuel. Maximum of around 3% these days.*

R134a Systems and new R1234yf refrigerant systems use around 2%. On more modern vehicles, The compressor works off ancillary or serpentine belts. These belts can be running water pumps, alternators, power steering pumps (not electric ones) etc. The clutch will disengage on the A/C Compressor when not required to save fuel.

On a motorhome, your alternator may be using quite lot too. As along with usual chassis system charging it has to carry out. It also has to charge your habitation batteries etc.

TM

*if you are running massive fleet of trucks, 3% is huge. On a motorhome, negligible in my opinion.
 

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