The grill ambient air temperature sensor should only be used for the air con/FBH/Heated screen/ice warning reference and display on the instrument info panel.
The air intake temperature sensor for fueling is contained within the MAF.

Thanks for the info. So could it be possible that the absent Battery enforced reset. Could affect the fuel consumption to that degree until the system settles down again. Eddie the eagle watch out 👀

If you disconnect the battery it will indeed lose the fuel trim numbers and will need to be relearned, it won't relearn them all until you go between every load and rpm combo in closed loop. As a guide I've always taken a tank of fuel as enough to say it's relearned back to where it should be. Having said that it shouldn't make a huge difference to the fuel useage unless there was something wrong and it was compensating with fueling (such as an air/vacuum leak).
In cold weather it will use more fuel as the air is denser so adds more fuel, conversely you will get slightly more power from it so for overall engine running there won't be a huge difference (unless you have a lead foot). There will be a difference in loads from extra electrical features used and warm up times compared to summer but again it shouldn't be huge unless it's left to sit and idle to warm up (I don't think the dash computer takes into account stationary fuel useage).
So you will use slightly more fuel in winter compared to summer but not drastically so (about 10% more in winter depending on your driving style).
I assume you are getting your mpg figures from the dash computer? Was your 11mpg doing exactly the same roads, in exactly the same conditions and over the same time period you got your 22mpg from?
Unless you are comparing like for like then I would take what it says with a pinch of salt and even then I wouldn't rely on it heavily.

Mine says it does 20-24mpg on the dash info but it doesn't, it does 17mpg from tank to tank fill which is bang on the manufacturers quoted average which I'm happy with given the driving I do. I have slightly undersize off road tyres hence the difference between the dash and reality. I could change the correction factor numbers (in the hidden dash menu) and get it to display whatever mpg I wanted to be honest but I just treat it as a guide but only if it's comparing like for like.

In your case I would run it for a tank full or two, working the mpg out from fill ups rather than the dash and then see what it's doing. If it's still using a lot of fuel after that then get the codes read and study the live data fuel trims.

Yep sound advice and I am not that anal about consumption figures.
I work on the precept that If I can't fill it up I don't use it.
Yes I could't agree with you more on your advice and appraisal.
But not knowing the intricate ways of the L322 M62 engine management.
I thought the quickest way to learn was to ask the people that do.
Many thanks it is people like yourself that take the time and trouble to share their knowledge that makes it feasible for the normal man to run a Range Rover. Hats off to you.
I will suck it and see how it goes. 👍🍻 Eddie the eagle watch out 👀

Pepi, the wire goes into the loom that picks up the left hand fog light then into the engine bay beneath the headlight, it could be chaffed somewhere and shorting the fog light and temp sender... you can get to most of it by removing the front undertray and left wheel arch liner....  Pete
__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand Sold
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Sold
2002 L322 Vogue 4.4 V8 Epson Green (Fatty Offroader) Sold
-Click for Project Fatty off roader-