Diesel MPG difference since the weather warmed up?
Discussion
fjord said:
The OBC in my car displayed 33.8mpg all through the winter.
Since it got a bit milder, and in the last week alone, it's shot up to 34.6.
Is it simply a case of the diesel liking to 'om nom nom' on warm air? Or is it making it heat up quicker?
Anyone else experianced similar?
Heats up quicker and think in April the pumps go back to summer fuel. Since it got a bit milder, and in the last week alone, it's shot up to 34.6.
Is it simply a case of the diesel liking to 'om nom nom' on warm air? Or is it making it heat up quicker?
Anyone else experianced similar?
BMW released and excellent tech note on how their computer works out MPG, the amazing bit was that before it gets to half temp it calculates 40% more fuel usage, which is how they have obviously programmed the ecu to fuel.
I had a day this year where my car didn't get to temp from Norwich till I got into Romford, it was -9°c outside, my mpg was 38, normally it is around the 50 mark.
That was taking it steady too.
Not forgetting of course that electrical stuff uses lots of energy.
First frost of the season this morning and the nights are drawing in as the clocks have just gone back. Diesel at 75p a litre helps.
(Not as good as it sounds, have to pay a mileage charge to use the roads with any fuel except petrol)
Cheers from NZ (with no recent earthquakes)
First frost of the season this morning and the nights are drawing in as the clocks have just gone back. Diesel at 75p a litre helps.
(Not as good as it sounds, have to pay a mileage charge to use the roads with any fuel except petrol)
Cheers from NZ (with no recent earthquakes)
k are you for it to have got milder!!??" gizlaroc said:
Heats up quicker and think in April the pumps go back to summer fuel.
BMW released and excellent tech note on how their computer works out MPG, the amazing bit was that before it gets to half temp it calculates 40% more fuel usage, which is how they have obviously programmed the ecu to fuel.
I had a day this year where my car didn't get to temp from Norwich till I got into Romford, it was -9°c outside, my mpg was 38, normally it is around the 50 mark.
That was taking it steady too.
Wait, so if it never gets up to temperature, it will throw 40% more fuel in?BMW released and excellent tech note on how their computer works out MPG, the amazing bit was that before it gets to half temp it calculates 40% more fuel usage, which is how they have obviously programmed the ecu to fuel.
I had a day this year where my car didn't get to temp from Norwich till I got into Romford, it was -9°c outside, my mpg was 38, normally it is around the 50 mark.
That was taking it steady too.
fjord said:
Wait, so if it never gets up to temperature, it will throw 40% more fuel in?
Which is ridiculous considering BMW thermostats break for fun.My 335d was averaging around 28mpg in winter with knackard 'stats. It never got above 70ish degrees when it should run between 88-92.
Changed the stats and it jumped straight up to averaging 32/33.. Now even more now its warmer.
fjord said:
gizlaroc said:
Heats up quicker and think in April the pumps go back to summer fuel.
BMW released and excellent tech note on how their computer works out MPG, the amazing bit was that before it gets to half temp it calculates 40% more fuel usage, which is how they have obviously programmed the ecu to fuel.
I had a day this year where my car didn't get to temp from Norwich till I got into Romford, it was -9°c outside, my mpg was 38, normally it is around the 50 mark.
That was taking it steady too.
Wait, so if it never gets up to temperature, it will throw 40% more fuel in?BMW released and excellent tech note on how their computer works out MPG, the amazing bit was that before it gets to half temp it calculates 40% more fuel usage, which is how they have obviously programmed the ecu to fuel.
I had a day this year where my car didn't get to temp from Norwich till I got into Romford, it was -9°c outside, my mpg was 38, normally it is around the 50 mark.
That was taking it steady too.
0-40°c was using around 40% more fuel
40-60°c was using around 25% more fuel
60-80°c was using around 10% more fuel
90°c it was at its most efficient.
They are not exact, but pretty close.
How long do you leave you choke out for when it is freezing??
I had a 3.2fsi V6 petrol A6 and on my 10 mile run into Norwich in the morning it would return 26mpg in the winter. I was lent a 3.0tdi for a week and that would return......25mpg.
Diesels take a long time to warm up.
The 3.0tdi was about 20% better on a run when warmed up though.
philmots said:
Which is ridiculous considering BMW thermostats break for fun.
My 335d was averaging around 28mpg in winter with knackard 'stats. It never got above 70ish degrees when it should run between 88-92.
Changed the stats and it jumped straight up to averaging 32/33.. Now even more now its warmer.
And the DPF doesn't regen till the car gets to temp either, so many DPFs getting replaced because the 'stat is knackered. My 335d was averaging around 28mpg in winter with knackard 'stats. It never got above 70ish degrees when it should run between 88-92.
Changed the stats and it jumped straight up to averaging 32/33.. Now even more now its warmer.
If you have a modern diesel treat the thermostat as a serviceable item, check it every month.
richardaucock said:
I run a Kia cee'd long-term test car and have noticed this too - in my case, the difference has been even more pronounced (5-6mpg on the trip).
Remember reading something about 'summer' and 'winter' diesel a while back: any fuel experts out there have more on it?
It was a while ago, but according to research myself and a member of another forum did, we found the switch date to winter fuel was 16th November, until approximately end of March. Looking at my fuelly records, my fill up before the 'switch date' was 65.7mpg. On my first fill up after the 'switch date' my fill up was somewhere around 60.1mpg. The temperatures in both weeks were the same (around freezing). Remember reading something about 'summer' and 'winter' diesel a while back: any fuel experts out there have more on it?
I believe it lowers the freezing point of the fuel from -5c to -15/-20c.
Sixpackpert said:
CraigyMc said:
Sixpackpert said:
fjord said:
Since it got a bit milder
Huh?
This week has not exactly been much warmer round here, not enough to see any fuel consumption difference IMO!
For what it's worth, in the South of England it's not unpleasant at the moment. The weather forecast is for 18C by the weekend.
C
CraigyMc said:
Sixpackpert said:
CraigyMc said:
Sixpackpert said:
fjord said:
Since it got a bit milder
Huh?This week has not exactly been much warmer round here, not enough to see any fuel consumption difference IMO!
For what it's worth, in the South of England it's not unpleasant at the moment. The weather forecast is for 18C by the weekend.
C
Sixpackpert said:
And in Gloucestershire only today has it even started to feel even remotely milder!
I was wandering about in shorts and a T-shirt on Saturday. South Coast (Southampton area). No wind. Sunny. I think the air temperature was about 10C, but in the sunshine it felt like summer.C
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