Has anyone else noticed increased fuel consumption during the recent cold spell ?
I have been getting 24-26mpg, but over the last 2 weeks, that has dropped to only 21-22mpg. I raised this with the dealer today and they suggested that it was likely to be the fuel heater because of the very cold weather we've been having.
Anyone else ?

Paul

I'd say he was right

Its winter diesel  Chips with everything

I also suppose the extra use of the seat warmers, heated screens etc all add their toll too. Matt
-------------------------------------------
RRS ownership for 1 yr, then D3 for 2 yrs. Then cut back to old bangers and working my way back up through two Peugeots in 6 months. Now got Saab 9-5 2.3t and enjoying the performance!

I think I've got to the bottom of the increased fuel consumption that I reported.
I stopped using the heated seats and although the weather is still cold, it hasn't been sub-zero here for a while, but I've still been struggling to get more than 22mpg.
However, I went out last night and on the outward journey, I averaged 22.7mpg, but on the return journey, I averaged 28.4mpg.
The difference ??
I filled up at a Shell station before returning home.
I've been filling up at a local Tesco for the past month or so and I can only assume that their fuel is of an inferior quality. I'll keep an eye on it and I'll try another tank full of Tesco fuel to see if the consumption goes up again.
I knew that all fuels weren't equal, but I'm amazed at the difference that this would suggest.

Paul

On long runs in weather as cold as we have been having I have found that my fuel consumption is generally a lot better once the car is fully warmed up - these are trips of 200-300 miles not wee runs around town! I put it down to the intercooler and Turbo working better at forcing more air into the combustion chamber. With my TD6 RR that I ran I was able to do the Stirling/Southampton run when the outside air temperature hovered round 1-2C all day and get the fuel consumption to 35mpg.........
Do you remember when Clarkson did the endurance run in an Audi A8 Tdi and was able to get much better fuel figures running without the Auto Aircon on or the heaters or the seat heaters etc and he froze for the trouble he went to.....

Do you put your Sport in a garage at night Paul? That also can make a difference on a cold day. My Td6RR and the TD4 Freelander that I ran had diesel powered heaters built in which also helped by being able to prewarm the engine before use, at the press of a remote control button. This doesn't appear to be even an option on the TDv6. 2020 Pangea Green 1st Edition D240 New Defender 110 is here and loving it
2018 Melting Silver Mini Countryman PHEV - soon to be replaced
2015MY Corris Grey SDv6 HSE Dynamic, the best car I have ever owned, totally reliable only a cou0le of rattles in 3 years, now no longer in my care
Also in my garage is a 1996 TDi300 Defender 90 County HT made into a fake CSW

Diesel engines are left efficient when cold than they are when warm, obviously , However, the difference isn't as marked as it is for petrol engines, they are much less efficient when cold.
I always have the air-con in ECON mode during the winter months. There's no point running a compressor to cool air that is already cooler than you want inside the car
The point here is that two journeys on the same evening, under the same circumstances gave very different fuel consumption figures with the only difference being the brand of fuel.
My RRS will go in my garage but I have two single up & over doors rather than one large one and it is a very tight fit Consequently, I tend to leave it out because I'm sure that one day, I won't be paying quite enough attention and I'll scrape it
I do indeed remember the Top Gear item. 800 miles on a single tank of fuel for a large exec car was very impressive. I've always had a soft spot for the A8

Paul

I agree with PaulB but there is a huge difference in quality of fuels and the the effect of winter diesel on fuel consumption.

With our experience with trucks we always see fuel consumption increasing by at least 5% up to as much as 12% when a diesel engine is working in the winter months on winter diesel and I see no reason why that would not be the same on diesel engined cars.

Effectively you have 4 type os fuel to choose from during the year;

Summer

A) 'Supermarket' or lower quality low sulphur diesel
B) High quality low sulphur diesel e.g. BP Ultimate

and during the winter

C) 'Supermarket' or lower quality low sulphur WINTER diesel
D) High Quality low Sulphur WINTER diesel e.g. BP Ultimate

And what is WINTER diesel?

Basically its a mix of diesel, petrol and other additives to prevent diesle from 'waxing' in the fuel lines due to cold temperatures. As a result of these additives the winter diesel does not burn as efficiently and this results in lower power outputs and higher fuel economy.

It is purely up to the fuel manufacturers as to when they introduce the winter diesel but you usually start to see it appearing from the end of November through until the end of March.

Also remember that the manufacturers deliver fuel continuously so even when winter diesel is first delivered its benefits are reduced as it mixes with normal diesel in to the petrol station tanks so the full effects of it may not be seen for a number weeks.

Hope this helps  Chips with everything

Thanks TC. I wasn't aware that diesel changed for the winter months.
I think I'll stay clear of supermarkets though from now on except for maybe one fill-up just to prove the difference.

Paul

So BP ultimate is worth the extra 3p? As for prices it amazes me the difference between stations - Clacket lane on M25 98.9p to a shell station near Sevenoaks 89.9p. My local sainsburys is 93.9p whereas as Local BP is 96.9p. Don't you love .9p why not round it up! 2005 Zambezi TDV6 - Gone but not forgotten
2009 Alaska TDV8 - Gone and much missed.



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Supermarkets are the same as Fuel suppliers!!

Sausages for £1.99...why dont they just say £2!!!  Chips with everything

It's a joke isn't it. It's like Mrs Va saying her new shoes cost £90.00 when they wer £99.99.  2005 Zambezi TDV6 - Gone but not forgotten
2009 Alaska TDV8 - Gone and much missed.



WINNER - 2009 �Idler Of The Year� Award
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Very Annoyed wrote:

It's a joke isn't it. It's like Mrs Va saying her new shoes cost £90.00 when they wer £99.99.

Yes, VA ...............but she knows you would shout at her if she told you she had bought a £100 pair of shoes doesn't she  2020 Pangea Green 1st Edition D240 New Defender 110 is here and loving it
2018 Melting Silver Mini Countryman PHEV - soon to be replaced
2015MY Corris Grey SDv6 HSE Dynamic, the best car I have ever owned, totally reliable only a cou0le of rattles in 3 years, now no longer in my care
Also in my garage is a 1996 TDi300 Defender 90 County HT made into a fake CSW

Very Annoyed wrote:

It's a joke isn't it. It's like Mrs Va saying her new shoes cost £90.00 when they wer £99.99.

Only £90 for a pair of shoes? There was a pair of shoes for £180 doing the rounds at Shmoogle Towers recently... until Mrs S decided she didn't like them after all and took them back (with gentle persuasion from me, of course)  

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