When I bought my 2005 4.4 V8 the display was showing 19.2 mpg average. The car has had a recent service at LR but has been showing average of 16.8 mpg this week. The car has been doing the same sort of runs since I bought it. Would it be the cold weather? Any other ideas? Also, it takes an age for the heater to kick out any decent heat.

Cold weather will definitely be having an effect.
Have seen mine drop over the last couple of days by 1-2 mpg. ON THE WAY: BMW F21 M140i
MERCEDES GL350 - Metallic Navy Blue w/Grey interior

GOING: BMW F31 335D MSport+ xDrive Touring
GONE: Land Rover Discovery 4 HSE - Stornaway Grey w/Black Interior (wish we'd kept it )
GONE: BMW F10 520D MSport - Carbon Black
GONE:MY12 RRS SDV6 HSE Sumatra/Ivory/Grand Black Privacy glass

Beancounter_74 wrote:

Cold weather will definitely be having an effect.
Have seen mine drop over the last couple of days by 1-2 mpg.

Heated seats, lights, etc etc all kill mpg RRS gone
Audi SQ5...Gone Audi Q7 S-Line 240 3.0TDI Gone
Audi A6 Allroad Sport 270 3.0TDI

awd man wrote:

Heated seats, lights, etc etc all kill mpg

Why would heated seats and lights affect mpg

I can understand aircon as it uses engine power for the condensor etc but not the above ! Proud owner of a 2008 TDV8 HSE.....and an Audi A3 2.0T DSG Cab and a Porsche 911 Turbo (Mercedes W208 320 CLK and Mercedes W124 E220 Estate now gone)

^^^ foe the same reason, they all drain power
I imagine the FBH also has a slight effect too as recently it's been in action every time I've driven somewhere  ON THE WAY: BMW F21 M140i
MERCEDES GL350 - Metallic Navy Blue w/Grey interior

GOING: BMW F31 335D MSport+ xDrive Touring
GONE: Land Rover Discovery 4 HSE - Stornaway Grey w/Black Interior (wish we'd kept it )
GONE: BMW F10 520D MSport - Carbon Black
GONE:MY12 RRS SDV6 HSE Sumatra/Ivory/Grand Black Privacy glass

RRS-Spy wrote:

awd man wrote:

Heated seats, lights, etc etc all kill mpg

Why would heated seats and lights affect mpg

I can understand aircon as it uses engine power for the condensor etc but not the above !

Where do you think the power for the heated seats etc. comes from?  2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

awd man wrote:

Heated seats, lights, etc etc all kill mpg

Alternator loads definitely pull power from the engine and therefore effect mpg; also in cold weather frictional losses can be higher will metal shrinkage. I notice the oposite more in the summer (higher mpg) on decent runs where everything is warmed up nicely.

This is happening to me also, showing 27mpg before service now 17mpg after  2.7 TDV6
22" Stormer alloys
Side steps
PS3
Headrest monitors
Black badges
Stainless tailpipes
Privacy glass
L.E.D. lights throughout.

Cold weather its self should increase MPG not decrease - given the cooler dense air.

And in modern cars the impact of additional load shouldnt be noticeable

However, the additional load will be noticeable on shorter journeys and FBH will nock a few MPG out of the systems Mike

2014 Facelift Discovery

mse wrote:

Cold weather its self should increase MPG not decrease - given the cooler dense air.

And in modern cars the impact of additional load shouldnt be noticeable

However, the additional load will be noticeable on shorter journeys and FBH will nock a few MPG out of the systems

I dont think we were disagreeing - its margins in a car that are small - definitely the lift from more dense air is noticeable.

But as we both said - FBH and short journeys (where the fuel into the DPF is highest) will kill you mpg not electrical load.

i bet if you compared normal summer use at points with winter - ignoring the heated screens/seats the use would be similar as i bet most of us run ac in the summer Mike

2014 Facelift Discovery

I run my aircon all year...it's "climate control" after all  2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed