Now we have our week of summer for 2008 with us I have noticed that my fuel consumption has noticably reduced and in local driving the trip computer is showing consistently between 29.1 and 30.7mpg. I haven't changed anything - I fuelled up on Monday at the local Shell station with ordinary and not Vpower as it isn't available here. 3 mpg extra out of a tank is useful extra miles to be getting at present prices!! The car has now racked up 8300 miles. 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

Warmer ambient air is less dense so less drag??? Cheers

Simon

2007 2.7HSE 20" Wheels
2005 TDV6 D3 S Auto - Zambezi Silver - JE Tune - RRS 19" - Sidesteps - Roof Rails
Body Side Strips - Xenons - Bright Pack - Cold Pack - Premium Stereo
Alpine Roof - Towpack - Alpine Touchscreen Satnav - Veba Rear DVD changer
Alpine Roof Monitor - Webasto FBH Timer - Brembo Frt & S/C Rr Brakes

It's still cheaper to fill up on a cold day! Maverick off disco3!
Drives white 1996 Defender 90 300TDi

R.I.P. Smudge! 24.10.08
R.I.P Hesko! 29.4.09

Tim, try taking ALL your clothes off before driving, see if the mileage increases further... You may be onto something!

Here in North America, there is actually an ongoing debate about the negative effect of warmer weather on fuel consumption. Backers of this theory say you get the most fuel for your money if you fill up early in the morning when the tanks at your local gas stations are cool, rather than later in the day when the sun causes their temperature to increase. Since fuel expands - volume-wise - with higher temperatures, and fuel pumps at gas stations are apparently not designed to adjust for that phenomenon (BIG SURPRISE!!!!), the theory says you actually get fractionally less fuel into your tank when the weather is warm than when it is cold, even though the pump says you got exactly 1 gallon... Which would lead to the assumption that actual mileage should decrease with warm weather, not increase. 

Probably just the running-in effect, Tim. Saying that, your mpg figures are amazing!

http://www.wthr.com/Global/story.asp?S=7348904

http://www.helium.com/items/241291-there-factors-cause-achieve

I wonder if there is such a thing as a "winter" and "summer" diesel formulation in the UK? That could make a little difference as well. 

Is your aircon running more? Is your sunroof open? Porsche Cayenne S Diesel 66 Plate

No sunroof! Climate is always set on 19 but now the compressor is having to work harder to cool the air so I expected higher fuel consumption not less - I wondered if the intercooler is working more effectively and cooling the charge air more. This is the first warm weather my TDv8 has been treated to as I took delivery last October. I see there is a thread over on Disco3 too about unusually low fuel consumption (ie they too are burning less go-juice!) 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

Tim, here's my theory.

Everytime you start the engine with the water temperature lower than it's operating temperature, extra fuel is being used until the operating temperature is reached. Now warmer air temperature's are with us, the time for the operating temperature to be reached is less and hence less fuel is consumed. If you keep an eye on the fuel consumption during the first few hundred yards travelled from starting up the engine, you will probably see the average consumption drop within that distance. The greater the drop in water temperature, the greater the fuel consumption will be - hence your greater mileage in warm weather. Gone - 2008 TDV8, Stornoway Grey, ebony, zabrano trim, TV, Tasmods, mudflaps.

Makes sense to me RR. I have also noticed that if I park the car nose into my drive (and faing west) where the bonnet is in the shadow of the rest of the car then the trip computer shows a bigger reduction in average fuel consumption than if I park it the other way round with the bonnet in the warmth of the morning sun...................... don't you just love these highly thermally efficient engines! Who says we don't try to be environmentally aware, just by parking the car facing into the morning sun I am saving the planet  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

It starts making economical sense to install a timer (or even better a remote start) to the Fuel Burning Heater for winter use. The only problem being voiding the warranty. Gone - 2008 TDV8, Stornoway Grey, ebony, zabrano trim, TV, Tasmods, mudflaps.

I've heard this mentioned before too (not necessarily here, but somewhere or other).... actually you only need to Google along those lines and there seems to be plenty of discussion. Some of it pointing to what Umberto was saying along the lines of winter/summer fuel blends from the pump. I'm not sure we get different fuels between summer and winter in the UK though... I suppose the temp differences here aren't that extreme between winter and summer to warrant it....  

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Hello Chaps,

we do get different fuel blends for summer and winter in the UK.
Usually imaginatively called D1 and D2.

The winter one (cant remember which) is thinner to help with cold flow and more anti waxing additives.

The summer one should give better mpg and more power.

Any petrochem boys want to explain why??

(removes anorak)...
Mart Jaguar XF 3.0D Portfolio
RRS TDV6 HSE 2006 , Zermatt , Gone

Perhaps you actually have had different fuel due to the Grangemouth shutdown???? Cheers

Simon

2007 2.7HSE 20" Wheels
2005 TDV6 D3 S Auto - Zambezi Silver - JE Tune - RRS 19" - Sidesteps - Roof Rails
Body Side Strips - Xenons - Bright Pack - Cold Pack - Premium Stereo
Alpine Roof - Towpack - Alpine Touchscreen Satnav - Veba Rear DVD changer
Alpine Roof Monitor - Webasto FBH Timer - Brembo Frt & S/C Rr Brakes

It's back open though now isn't it? 

2009 Outstanding Contribution Award - Joint Runner Up
2009 'Tech-Head Of The Year' Award - Runner Up

Like it here? Then Donate to RRSPORT!!