Have noticed that during the cold weather my average MPG has dropped by 2-3mpg on my tdv8 to round about 21-22 mpg and the FBH has been running almost every journey. Have been using my car everyday for work (rural roads) and didnt expect much more to be honest but yesterday i fueled my car up (8 degrees) and reset the trip and when i got home i had gone back upto 25.4 on the same roads

Is it possible that the FBH is costing me 2-3 mpg because before the cold spell i was also getting 25+mpg
Paul Current fleet
2011 Discovery 3.0 sdv6 XS
2008 Range rover sport HST tdv8*gone*
2000 Porsche 911 Carrera 2 convertible
1996 TVR Chimaera*gone*
2004 Vauxhall combo van*dead*
2003 ford ranger double cab

The FBH uses 0.6l/hr at full load, 0.35l/hr at part load. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

Fuel economy on any vehicle goes down during cold weather in my experience  Wanted a Series 2 LR since childhood but previously owned MY16 Disco Sport HSE TD4 Auto, MY13 RR Sport Black Edition TDV6 Auto, MY10 RR Sport HSE TDV6 Auto, 2007 Freelander 1 Freestyle TD4 Soft Top, 2009 Freelander 2 GS TD4 Auto, 2007 Freelander 2 GS TD4, 2004 Disco 2 Metropolis Auto, 2002 Disco 2 GS, 2000 Freelander 1 SE TD4 SW

Still hoping for a S2 one day!

I have exactly the same, high 20s in the warm weather on a long run and now down at 22 since November even on a couple of hundred miles trip. Combination of heater and cold temperatures I guess. Nice to know others are getting exactly the same numbers! TDV8 Java Black, Overfinch 22s

I have heard that the additives in the diesel in winter to protect against freezing can have a detrimental effect on MPG.

Thanks all Must be a combination of heated seats/windows and the FBH that has hit my mpg. See how it goes when it gets warmer  Current fleet
2011 Discovery 3.0 sdv6 XS
2008 Range rover sport HST tdv8*gone*
2000 Porsche 911 Carrera 2 convertible
1996 TVR Chimaera*gone*
2004 Vauxhall combo van*dead*
2003 ford ranger double cab