I'd like to get to the bottom of the poor MPG and performance I get in my Fabia VRS when the weather is cold.

I've always accepted a relatively poor MPG in the winter as a consequence of the low temperatures and 'winter diesel' - but this year has been the worst ever for me. On a steady (70 mph) motorway run to work (30 Miles) I've been getting an indicated 50mpg and a calculated 48mpg.

Coupled with the poor mpg I've been getting poor performance - the car just sounds rough and feels like it doesn't want to go.

Yesterday the temperature reached a tropical 8 degrees C where I am and the same journey saw an indicated 60mpg and much improved performance.

There are no error codes - I've scanned the car with the Torque App on my phone. Does anybody have suggestions of what could be wrong?

-Fuel temperature sensor?

-MAF?

-Coolant temp sensor?

I found a good improvement on mpg with a service changing diesel fuel filter but I also notice the symptoms you describe with cold weather but mine drops to around 35 mpg and seems to be lethargic.

We've had the second coldest March on record with an average temp of only 0.3c higher than the lowest, you said it yourself the when the temp goes up so does your mpg, this suggests nothing is wrong with your car at all. Remember at 0c the wind chill is getting on for -11c from memory at 70mph.

Edited 3 April, 201313 yr by Avalon

As above, the car takes an age to warm up in this weather twinned with the winter diesel will have a big effect. Could be worth changing filters anyway.

I knew it had an effect, but never realised it was so great.

It's just a combination of speed and ambient temp, combined with the thermal efficiency of the PD. I've driven at -11.5c ambient, that's -28c at 70mph, strangely enough my mpg wasn't so great that week.

Mine is the same really noticeable drop in mpg this winter. I'm sure its not meant to be like this. I can't see them designing a car the drops nearly 20% fuel economy depending on weather. Fuel temperature sensor hmm not sure if these can fail but i'm gonna change it on mine anyhow, clutching at straws again. My mpg never suffered at all last winter . It seems like quite a few of our cars have developed the same problem and the garages are stumped / don't want to know. My local skoda specialist just said they would change all the bits i have already replaced so no help there.

Edited 3 April, 201313 yr by RAPTURE

The fuel filter is about 10 000 miles off being renewed. Oh well, just have to put up with it I suppose.

I've got the same problem guys, where I used to get 50mpg now I get about 45, basically impossible to get over 50mpg on a motorway run where as I used to get about 56mpg. ****ing me off, read about changing the MAF?

What's that saying about leading a horse to water?

A 5 mpg drop could well be the weather. I am talking 10-15 mpg.

My summer averages were 58-60 in my 1.9TDi 100, around 50-52 since late December.

Just presume we have to live with it...

Of course the current high winds are also having an effect on the drag, too.

Edited 3 April, 201313 yr by Oli3000

didn't want to exagerate ! but an example I encountered was sometimes where I reset the mpg after joining the motorway I could make it from livingston to hermiston gate (about 10 miles) with something crazy like 65mpg. If I try that now, i'd be lucky to break 52mpg

I don't think mines dropped that much tbh, maybe 2 or 3 mpg but nothing that drastic really. I'd be tempted to say Maf or coolant temp sensor playing up, more tempted to say the coolant temp sensor

A 5 mpg drop could well be the weather. I am talking 10-15 mpg.

You say above it's 'almost 20%' above so you're getting almost 75mpg? If so what car are you driving exactly and how are you calculating those figures as most SDI owners would be jealous of tank averages like that, let alone a PD100/130 owner.

Mine is the same really noticeable drop in mpg this winter. I'm sure its not meant to be like this. I can't see them designing a car the drops nearly 20% fuel economy depending on weather. Fuel temperature sensor hmm not sure if these can fail but i'm gonna change it on mine anyhow, clutching at straws again. My mpg never suffered at all last winter

It's not designed to drop '20%' economy in cold weather.....it's just the way it is.

It's April now....Definitely don't start replacing parts.......wait another month or so, when it will be significantly warmer.....then access your MPG. Last winter was not nearly as cold as this winter which may be why you are noticing it this year.

Mines is the same, 40-50 mpg in the cold mornings over a 50 mile drive and on the way home i average 60-65 :/

On the dis obviously lol. Ive actually seen 70 odd on a drive home!

Mines is the same, 40-50 mpg in the cold mornings over a 50 mile drive and on the way home i average 60-65 :/

I'd say it's far more likely that your trip to work is uphill. Such a small temperature difference is unlikely to have such an effect. We're talking between 0c and 20c ambient temps

My average on Fuelly fluctuates with the seasons as well. I get about 58 average in the summer and barely touch 50 in the winter. Maybe we should block our radiators in winter like the Landy guys do, and intercoolers for that measure

Edited 3 April, 201313 yr by Ben90

You say above it's 'almost 20%' above so you're getting almost 75mpg? If so what car are you driving exactly and how are you calculating those figures as most SDI owners would be jealous of tank averages like that, let alone a PD100/130 owner.

My car is as pictured a PD130 ASZ. I used to get 65-70 on a cold morning driving 5 miles to work, yes just five miles driving would show this figure on the dash and my fuel would hardly drop all week. Now im getting worst case 36, if i drive like an angel 40 ish on the same journey and i can see the guage drop. So the drop is in line with what others have mentioned in this tread that own the same car as me. I see from your sig you do not own a VRS. I dont know where you get the idea a sdi is more ecomomical than a pd 130 ? my car has covered 59000 miles. One thing is traffic, which there is more and more off all the time. The 32mph brigade around here seem to have turned into the 25mph brigade so I cant get in 5 gear very often around town anymore, a contributing factor I guess but it drinks more at a steady 70mph than it used to. I will be taking it for a long drive to Devon soon, maybe that's all it needs is a really long run.

Edited 4 April, 201313 yr by RAPTURE

My car is as pictured a PD130 ASZ. I used to get 65-70 on a cold morning driving 5 miles to work, yes just five miles driving would show this figure on the dash and my fuel would hardly drop all week. Now im getting worst case 36, if i drive like an angel 40 ish on the same journey and i can see the guage drop. So the drop is in line with what others have mentioned in this tread that own the same car as me. I see from your sig you do not own a VRS. I dont know where you get the idea a sdi is more ecomomical than a pd 130 ? my car has covered 59000 miles.

Is that 65-70 backed up by working it out brim to brim? Seems high I've never got more the 55 out of my asz and that's doing 50 on a dual carriageway

No that's on the dash and my wallet. If i cant trust my computer then why has it changed so much ?. It was steady for 2 years and now behaves differently. Maybe it was wildy optimistic before and now is more accurate, but i kinda liked my wildly optimistic dash reading . I have not adjusted the value in vagcom btw. I will do a brim to brim when i can afford it lol. I only usually fill my tank to half.

My car is as pictured a PD130 ASZ. I used to get 65-70 on a cold morning driving 5 miles to work, yes just five miles driving would show this figure on the dash and my fuel would hardly drop all week. Now im getting worst case 36, if i drive like an angel 40 ish on the same journey and i can see the guage drop. So the drop is in line with what others have mentioned in this tread that own the same car as me. I see from your sig you do not own a VRS. I dont know where you get the idea a sdi is more ecomomical than a pd 130 ? my car has covered 59000 miles.

I'm on a mobile device, your picture is less than half the size of a postage stamp, I can tell you it's a silver fabia but that's about it hence the question.

Your figures make slightly more sense now I know you're using the trip computer to guess the mpg as it's known to be less than accurate through to wildly optimistic. On the PD Golf or Octavia or A4 (i've not looked on the PD Leon yet as like 'stupid wipe' it's not annoyed me enough yet) you can recalibrate the correction factor with VCDS, but as you've noticed a Fabia with a PD block is one of the few I haven't owned or been asked to do it on. The generally accepted method for measuring mpg is by doing brimmed fills as it's a fixed point of reference (well as close as you can get, vented fills and air locks aside), you record the volume of fuel put in, the cost and the distance you travel, this allows you to calculate mpg and cost per mile. Ideally you average the figures over a few tanks to reduce the effect of air locks/venting, this gives you a reasonably accurate figure. Without this you have no accurate basis for comparison with anyone else's figures which may explain why your claims are up to 32% above the combined book figure, on a 5 mile commute 'on a cold morning' you'll get nowhere near that economy, no matter what your trip computer tells you.

As to your point about my knowledge of TDI's i've owned and looked after quite a few and done a good few hundred thousand miles in them, the last being my mapped PD100 DSG which would be comparable in terms of output to your VRS and similar to the PD140 I have now or the PD130 A4 I had before. The PD lump is a thermally efficient engine, unlike a petrol it takes longer to warm up and get to a point where it's capable of operating efficiently and returning the mpg it's known for, 5 mile commutes are never going to give you the combined cycle figure of 53mpg let alone the 65-70 you're claiming, though your previous almost 20% that you suggested comes out at 75mpg so would it be fair to say you were optimistic with that as well? To suggest it can return the figures you claim (that's 22-32% or almost 1/3 over combined cycle figures) is pretty dubious, to claim that on a 5 mile cold journey is just silly unless you're rolling down a hill etc.

The comment about your fuel doesn't drop is because by your own admission you do 5 miles each way, how can you possibly think it would move doing 50 miles a week? My needle doesn't budge for the first 150-185 on a vented fill on the mpi and 100ish unvented, the Leon is about the same on a normal fill, no venting required. You aren't trying to compare results on partial fills are you as that's even less accurate.

As to why I would think that an SDI that's booked at 57mpg on a combined cycle is more economical than a vrs booked at 53mpg, its to do with the difference between the two numbers Add the real world figures provided by others who can calculate mpg in the normal manner and it's an easy mistake to make

I'd be very surprised if you were getting 65-70 mpg out of a PD130 on a 5 mile commute......unless you live at the top of a mountain and the 5 miles is all down hill!

My record (calculated) MPG in my PD100 is 68 MPG......on a 20 mile commute, mostly on A roads and Motorways....at 6am when there was no traffic. Even so, I had to drive it very carefully to get that figure....by careful I mean anal use of hypermiling techniques.....I don't thing I touched the brake during the whole journey!

If you are going by your wallet for fuel consumption data, remember fuel prices have gone up by about 5p/litre since Christmas.

As Avalon says, you can adjust the MPG readout on the Octavia/Golf platform, but not possible on the Fabia.....I've tried it a few times without success.

Edited 4 April, 201313 yr by booke23

All valid points and I thank you for the advice. I did not want to hijack this tread but I am getting a cloud of white smoke at start up now when left overnight which smells bad and enters the cabin in the morning. It is not just the water in the exhaust evaporating, clears as soon as I drive off and does not return untill left overnight again. I am inclined to think its connected to my issues.