Picked up my brand new Octavia 1.9TDi Ambiente 11 days ago and so far, so good. I had been looking at a supermini for the economy but the extra space in the Octavia won me over. Plus my previous car (a company car) was a VW Passat and I think the drop from that to something like a Ford Focus would have been too much. Back in the good old days when the company also paid for the diesel in the Passat I never worried too much about economy. but now I have to pay for fuel, I'm a lot more careful. According to the trip computer my 30 mile commute this morning returned more than 70 mpg. Except the only time I have put fuel in the car the trip mpg seemed to be overstated. Something to watch out for. Anyway, I'll get to the point of this post. In the Passat I never noticed what effect the air-con had on mpg. In the Octavia it appears to be quite dramatic. Obviously it's almost impossible to check on public roads but the mpg seems to drop by 5 - 10 mpg or at today's prices between 2 & 3p per mile. Has anyone here ever tried to test the effect of air-con on mpg? In fact this is about the only area (except lack of mp3 connection in this model; something I intend to remedy) that I don't like. Methinks the Octavia and I are going to get along real fine!

Mine will only drop about 2mpg roughly but i have never really calculated it correctly.Just something i have quickly noticed when its on.

I haven't checked the effect on mpg for my 1.9TDi but I have noticed thatunlike some cars (especially swmbo's 1.4 Micra) that I don't feel any reduction in power when I switch it on.

My old Fabia vRS' MPG dropped by 1 with the A/C on

Five summers ago when I and a then-colleague were both running Mk1 vRS (petrol), my colleague (who some might characterise as a "canny Scot") pointed out that his mpg had been rather hit since the summer began and he'd been using his aircon. A couple of weeks later he mentioned that most of his fuel economy had been restored since he had made sure the "Econ" button on his aircon was activated. Looking back at my figures, I reckon it made about 1.5 mpg difference.

Don't know what difference it makes on my current car, as I now pretty much always run the aircon in Econ mode except for the odd occasion when I need to rapidly demist or really need to cool the car down quickly.

Well, yesterday I got my Octy Elegance back after having its new compressor fitted and I don't care what the drop in mpg is. After 4 weeks of no a/c it was lovely to get that draft on my face going up to London and back.

Skodas are cool.......again!!!

Use the econ button to get the MPG's back

not noticed it in my car, if there is its a very small amount.

over the past 6 or 7 weeks while the weather has been good my better / prettier half has been using the aircon a lot and we've noticed maybe a 50 mile decrease in range from a full tank of diesel - power seems unaffected. i just have the boggo manual aircon on my classic so no economy mode :(

Use the econ button to get the MPG's back

True but I gather that econ can't get you any cooler than the outside air temperature, so for coolong purposes is not much better than just having the fan on.

Econ disables the aircon completely, so no cooling.

TBH in my 2.0TDi with dual zone, it doesnt make any noticable difference in power/mpg if the a/c is on or off.

Odd.

SWMBO fills weeekly with econ, every 3 days without. And she's fussy about being too hot, so AC must be working?

I though it reduced the climate control continuously turning on/off to maintain the desired temp (like home heating), yet in econ allows more leeway +/- desired temp

It doesnt make a blind bit of difference in my vRS. If it does then it must be miniscule

Carl

Odd.

SWMBO fills weeekly with econ, every 3 days without. And she's fussy about being too hot, so AC must be working?

I though it reduced the climate control continuously turning on/off to maintain the desired temp (like home heating), yet in econ allows more leeway +/- desired temp

I thought the book just said you can't go below outside ambient air temp on econ. It still works as climate control, but only if the cabin temp you want is above that of the outside air, so unlike a heater it still keeps cabin to a set temperature.

Thanks for the info folks

The consensus seems to be that any effect is reasonably small. I guess I'll just have to keep an eye on mine.

I have noticed in my wife's Golf 1.9DSG a more noticeable affect from A/C than on my Octy II 2.0 DSG. It may be an engine thing...

The econ button means no cooling, the system can, and will, bring the car up to a temperature you set above ambient. Doing so it uses the heater and will stop when the temperature reaches that desired, topping up with warm air as required. It does not use the air conditioning unit to do this, just the heater. Cooling can only be carried out with the aircon on, though you can take advantage of the dehumidifying effect of it with the temperature set to any level - such as heating/aircon on for demisting.

Using the aircon (auto) will use fuel as you are then driving a compressor, the amount that this affects the fuel consumption will depend on the existing temperature, if hot there is more work to do. A journey starting with a hot interior will mean ac using a lot of energy to get the air cooled down, once cooled it can reduce its workload and tick over. So the additional fuel tends to be noticed on short journeys and little effect on longer ones. More consumption would actually result from opening a window at higher speeds, due to aerodynamics. So short slow speed journey - ac off (econ) and window open instead, faster speeds and longer journeys - enjoy that cool breeze with windows firmly shut.