Hi All,

My Fatty is a motorway queen. I travel from London to Pembroke every week and it is a total is 500-520 miles round trip. I sit in the top lane with radar cruise set at 80 leptons and I normally get 36 mpg, which is almost a full tank and has about 40-60 mile range when I get back home.

Last few weeks the car is struggling to get 31+ which is a significant drop. Can I simply put this down to winter diesel?

Car performance and drives like brand new, with 135k on the clock and I think she will do another 135k with ease.

Any thoughts welcome. I've been doing this trip for the last 12 months so something is definitely off.

IceBoy

Winter diesel would be my prime suspect. 2012 Vogue TDV8 in Aintree green over sand

Check to see if any of your wheels are warm - might be a slightly binding calliper.

I assume your true pressures are within range too.

(Start with the cheap stuff first lol)

Dave

 All things transport - big or small, UK or planetwide.
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Tyre pressures are good but I will check to see if the callipers are binding...good shout.
IceBoy

How scientific is your recording… are you going by the dash or a physical refill and number crunch?

If winter diesel caused such a drop off, which I doubt, the haulage industry would be screaming for change to get back the missing 12% drop off, in economy.

its more likely the drop off in efficiency with cold engines, diesel engines take an age to thoroughly warm up. Truck engines shouldn't ideally ever get cold. First time FFRR owner

I'm surprised with you getting 36mpg at 80mph from the SDV8.

I measured mpg regularly using the full to full method over 4 and half years (it always said slightly better mpg on the computer than I could get in real life).

My normal mpg was about 28-29, although I could get 32 on a run. The best I got was 33.25 when I kept the speed below 70mph (the computer said 36.0). Current:
- 2017 L405 3.0 V6 Autobiography
Sold:
- 2013 L405 4.4 TDV8 Vogue
- 2004 L322 4.4 Vogue (BRC LPG)
- 2002 L322 4.4 HSE (having fixed timing chain guides)
- 2000 P38 4.6 Vogue (BRC LPG)
- 1981 2-door In-Vogue
- 1980 Ex-Army SIII LWB
- 1976 SIII LWB
- 1968 SIIA
Stripped for parts:
- 2003 L322 4.4 Vogue

I think the FBH must add quit a bit to total fuel consumption at this time of year

Dpf regening more than it should be? Cheers

James

Hello All,

Bit of an update, I checked everything and the tyre pressures were down by 1 or 2 psi, so not much. Everything else is spot on.

I think the combination of winter diesel and cold weather has had the negative effect on the economy. It's not too dramatic and first world problems really but thought I should report back.

FYI, my monitoring and calculations are very detailed and accurate as I have to report these for business purposes.

Thanks all and happy motoring.
Iceboy

I'd go with Dtech, more than likely the FBH Current
2017 Range Rover Sport SVR
2001 Porsche 911 Turbo
_____________________________________
Previous
2013 Range Rover Autobiography SDV8
2007 Range Rover Vogue SE TDV8
2002 Range Rover HSE TD6
+ Many other non LR products

JST wrote:

Dpf regening more than it should be?

Try this. Not a light read though!

BTW I’d echo the comment above with surprise that you were getting high 30s when cruising at four score. I only get 32ish if I keep to 70. 2016 SDV8 AB

DPF regeneration has an insignificant effect on mpg. Typicaly it takes 10 miles at motorway speed at a 10mpg loss. The FBH will hit mpg more as will cold air temps generaly for low load cruising. 2012 TDV8 Vogue (L322)

I did 2 return trips from Glasgow to Aberdeen last week, used the FBH each time and returned just under 37MPG at a steady 65MPH. Got - 2017 SDV8 Autobiography in Loire Blue
Had- 2008 TDV8 Vogue SE in Java black
Had - 2007 S/C in Stornoway Grey