Just noticed that the front screen & rear window electric demisters / heater elements are automatically switched on when I start the engine.

Is this a software fault, a menu option, or is the switching on triggered by sub-zero temperatures ? Thanks Nick

Mine does it too. It only happens in low temperatures and appears to be a function added by LR during the facelift. Earlier RRS didn't do it. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

This explains why the battery is nearly flat all winter time

Only if you do short journeys, I would suggest. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

Mine does this every time you start the car if the temp is low and the snow flake is displayed. 4 degrees or below I think.
No snow flake, No heated screens coming on. 2019 4.4 SDV8 Autobiography Velocity blue.
2017 SVR. SVO Scafell grey Ebony interior. Gone
2012 3.0 SDV6 Autobiography santorini black with ebony/cirrus interior. Gone

Indeed so. They can be turned off by pressing the buttons so it's not a real issue. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

That's exactly what I do if they don't need to be on. 2 button presses problem solved 2019 4.4 SDV8 Autobiography Velocity blue.
2017 SVR. SVO Scafell grey Ebony interior. Gone
2012 3.0 SDV6 Autobiography santorini black with ebony/cirrus interior. Gone

My heated rear screen is on even when the buttons aren’t turned on,,must be a fault on it so I’ll mention it to LR when it goes in for next service

Andy Andy.
21 Ford Ranger
Gone but not forgotten
Focus RS Red Edition
2015 RRS AB Fuji.
2014 RRS SC Santorini
2016 VW Amarok
2014 RRS AB Fuji
2012 RRS Red Edition Fuji
2015 Nissan Navara
2012 RRS SE Santorini
2008 RRS White
2007 RRS Santorino