Cold weather makes havoc of fuel economy

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Mon 8 Apr 2013 15:25
Cold weather makes havoc of fuel economy - Happy Blue!

My S-Max (diesel auto) has averaged 33.4mpg since the day it arrived with 11,000 miles on about three years and 29,000 miles ago. I reset the trip computer when it arrived and after a week or so, it settled down to 33.4mpg and has not moved from that unless I have done a very long day of motorway driving which has pushed the average up by a couple of notches, only for it to drop again within a couple of days of regular urban use.

Just noticed that the economy has dropeed to 33.3. Nothing huge of course, but unless there is something wring with the car, I assume this is the affect of a sustained period of cold weather?

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Mon 8 Apr 2013 15:50
Cold weather makes havoc of fuel economy - unthrottled

A 0.3% drop-Havoc indeed!

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Mon 8 Apr 2013 16:17
Cold weather makes havoc of fuel economy - madf

Margin of error stuff.

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Mon 8 Apr 2013 16:56
Cold weather makes havoc of fuel economy - bathtub tom

Your tyres have worn to a smaller diameter.

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Mon 8 Apr 2013 18:35
Cold weather makes havoc of fuel economy - Drivethru

OMG how do you sleep at night with such a problem to solve.

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Mon 8 Apr 2013 18:59
Cold weather makes havoc of fuel economy - Alby Back

33 point anything would seem low to me for such a car. Presumably you drive short runs in heavy traffic mainly? Or is that what's pretty much expected from that model?

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Mon 8 Apr 2013 19:27
Cold weather makes havoc of fuel economy - Andy P

I must be doing something right - my 335d has just crept up to 35.3mpg average. I'm obviously not trying hard enough.

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Mon 8 Apr 2013 20:12
Cold weather makes havoc of fuel economy - bucca

from what your saying that is the average of 29,000 miles of driving? try resetting every now and again i.e if i drive to work and back every day 15 miles each way i get 40 mpg but if i reset and do a 200 mile blast on motor way i get 49 mpg i even check it by brimming tank and working it out computer is always 1mpg over optimistic

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Mon 8 Apr 2013 20:46
Cold weather makes havoc of fuel economy - BigJohnD

Fit a winter grille....

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Mon 8 Apr 2013 21:54
Cold weather makes havoc of fuel economy - coopshere
I always thought the whole point of having a diesel engined car was for better fuel consumption. Most modern petrol engined cars will beat that hands down and petrol is much cheaper than diesel too with none of the smell, noise, vibration or inherent problems either. Time to move it on I would say.
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Mon 8 Apr 2013 22:25
Cold weather makes havoc of fuel economy - Alby Back

Well, it might perhaps be a bit of a challenge to find a large 7 seat automatic petrol car which would reliably do better mpg than the OP's but I'd be mildly disappointed maybe by the "economy" of the diesel car mentioned I suppose. I would have, perhaps naively, thought it might have been a number closer to 40 than 30. Of course it may be the uses / types of journeys to which it is normally put having a strong influence.

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Mon 8 Apr 2013 22:26
Cold weather makes havoc of fuel economy - Avant

Remember that it could be a drop from 33.36 to 33.34, depending on how the trip meter does its rounding. So it may not be a significant problem. That said, I think cold weather can make a difference: I'm sure an expert will be along soon to put us right.

Interestingly, 33.3 mpg is exactly the same figure as my petrol DSG Octavia 2.0 vRS has averaged over the last 2,000 or so miles. Much of the mileage is short 4 or 5 mile trips, with a longer journey about once a week. On a good long motorway run it does a very sporting 38 mpg: if I kept down to 60 mph I could get over 40 mpg easily.....but if I was going to drive like that I wouldn't have had a vRS in the first place.

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Mon 8 Apr 2013 22:42
Cold weather makes havoc of fuel economy - gordonbennet

I too don't reckon much to the average consumption of Happy Blue's Mondeo on steroids.

My 2 ton brick Hilux 3 litre auto managed just under 30 average, and that was permanently dragging that industrial quality tranmission around on huge tyres, and my Mrs doesn't compute the word slow.

In a previous discussion we suggested giving that car of yours a birthday HB, full and intensive service including a full brake service...not a fast fit fitters blast with a can of brake cleaner or lift the bonnet briefly then squirt white grease at the door hinges kind of service.

Would be interesting to see the economy difference after a proper mechanic has spent half a day fettling.

Funnily enough on a similar fuel tack though, my new lorry is now about 8 weeks old and on 28k kms, its average consumption has crept from 7.6 mpg up to 8.2 over that time, with a peak of 9.0 on Saturday...how much of this is down to starting to run in i don't know but i shall be monitoring economy with interest as the weather warms up...then when winter starts again in July watch it plummet again..;)

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Mon 8 Apr 2013 22:52
Cold weather makes havoc of fuel economy - Alby Back

"Mondeo on steroids"

Come now GB ! Although, a good pal has a Mondeo 2.0 diesel auto estate which is about 3 years old so might be at least similar mechanically. He claims that it gets 45mpg reliably and rather more on a long run. Of course he may be relying on a fork-tongued trip read-out or indeed he may just be fork-tongued himself. Wouldn't like to say. Funny thing to tell tales about though if he is. Takes all sorts I suppose.

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Mon 8 Apr 2013 23:07
Cold weather makes havoc of fuel economy - gordonbennet

I'd have expected the barge like S max van thingy to be about 5 mpg short of the reasonably streamlined and low Mondeo van AB, not the huge difference we see here.

I don't disbelieve your mate*, a good well maintained modern Diesel should return those figures on a run, i would have thought HB should be seeing 40 regularly.

*fortunately as its an auto it won't be stalling every other standing start..:-)

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Mon 8 Apr 2013 23:16
Cold weather makes havoc of fuel economy - brum

Look on the bright side, if we have a scorching summer, it may go up to 33.5! But then again, maybe the aircon will drag it down......

Probably best to change the car for a new one, just in case there is something "wring"!

;)

Edited by brum on 08/04/2013 at 23:16

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Tue 9 Apr 2013 00:49
Cold weather makes havoc of fuel economy - veloster

is this a wind up or what

"happy blue",,"something wring",,,,"33.4mpg to 33.3mpg"

got to laugh at this thread

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Tue 9 Apr 2013 09:23
Cold weather makes havoc of fuel economy - Happy Blue!

I'm not making it up nor am i complaining.

The point I am makingis that statistically, a drop from 33.4 to 33.3 is interesting given that it has happened over the last three or four weeks of cold weather and the trip meter has not been reset for 29,000 miles.

I am happy with the economy. My driving is such that I have rarely acheived better than 20mpg from a petrol car. Its not that I drive fast (I don't) but that I do a lot of stop start driving around urban Manchester.

I know that on a run (I drove 520 miles a few months ago from Manchester to Alloa and back via Paisley), I achieved over 40mpg for the day.


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Tue 9 Apr 2013 10:44
Cold weather makes havoc of fuel economy - skidpan

"I always thought the whole point of having a diesel engined car was for better fuel consumption. Most modern petrol engined cars will beat that hands down and petrol is much cheaper than diesel too with none of the smell, noise, vibration or inherent problems either. Time to move it on I would say."

Total nonsense. We run a diesel Kia Ceed SW. In 25,000 miles we have averaged 51mpg. Owners of the same car with the pertol engine average about 35 mpg according to various websites.

By my simple calculations we have saved 224 gallons of fuel. Factoring in the 4 pence per litre difference and using todays cost at the pumps we have saved £1296 in fuel plus about £200 in RFL costs, altogether about £1500. Servicing costs exactly the same.

As for smell, noise and vibration you obviously have not driven a modern diesel.

With regards to problems I think that is the luck of the draw. Not had a problem with either a diesel or a petrol ever.

Remember that the OP is driving a S-Max auto and not a small city car. If you can suggest an auto 7 petrol car of the same dimensions that will do better than 33/34 mpg in the same type of use please tell us.

With regard to the Mondeo comparison we had a TDCi 130, the wifes commute was about 8 miles across town plus it did motorway miles to the outlaws and holiday runs. Over 30,000 miles it averaged 38 mpg therefore 34 mpg out of an auto S-Max looks pretty good to me.

Regarding the OP's original question a bit of maths reveals the simple facts. While he has owned the car he has covered 18,000 at an average of 33.3 mpg according to the fuel confuser. That is 540.5 gallons used. Assuming this recent drop has taken place over the last 1000 miles he did 17,000 miles at an average of 33.4 mpg using 509.0 gallons. Bit more maths means he has used 31.5 gallons over the last 1000 miles, yet more maths shows the average for those 1000 miles was 31.75 mpg.

Hardly significant and almost certainly due to the cold weather and the simple fact you always get less mpg out of winter diesel.

Edited by skidpan on 09/04/2013 at 10:55

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Tue 9 Apr 2013 13:42
Cold weather makes havoc of fuel economy - davecooper

Very cold weather does seem to make a difference, about 5mpg in my Mazda petrol.

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Tue 9 Apr 2013 15:22
Cold weather makes havoc of fuel economy - Drivethru

is this a wind up or what

"happy blue",,"something wring",,,,"33.4mpg to 33.3mpg"

got to laugh at this thread

I checked to see if it was still April 1st, even more unbelievable is the amount of people who have bothered to reply!

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