Had another look today, last week put some scrunched up newspaper behind left hand cubby in boot , so below rear light, had a look today ,little bit wet, definitely damp, think it's coming in around rear light, so have put a thin smear of mastic along top of light, put new dry paper back in and will monitor over the next few days

Andy

I noticed today my load cover was wet, on further inspection it's coming in through my brake light so I've siliconed it so I will check again tomorrow.

So the mastic round the light seems to have done the trick in the boot , but still occasionally having issues with the screen, am thinking now that the water is sitting somewhere in the air intake, as the moisture forms on the screen directly above the vents, car is completely dry, is it possible that water is getting in prior to the pollen filter and then the air coming into the car is bringing the moisture in with it?
Think I saw on here someone had a problem with water entering the front wing through the intake
Andy

Really getting fed up of this now, this week car has been misted most days, clears quite quickly but still bugs me😟 interior is bone dry, if you look at where wipers are in front of wiper spindle nearest to centre of car are two small holes, would these be additional drain holes? Anyone know if theirs a way to test that all the flaps associated with heating / ventilation are working other than fan on and moving rotary dial as done that and seems ok , but I think it's an airflow issue when car is turned off that's causing this ,would it be controlled by a module of some sort or independant servo
Andy

Something to check:

Where the rain/water drains away from the bottom of the windscreen, there are channels that direct it across and down towards the floor within the engine bay. With the bonnet up you can clearly see this (all black plastic) at the bottom of the windscreen. On either side above the wings there is an oblong rubber flap, lift this up and as like I did, you will find 4 years worth of leaves, dirt, pine needles and a multitude of other crud blocking the designed natural flow of the water.

Remove all this crud and give the area a quick rinse to get rid of the remaining crud and see if that makes any difference..... MY2010 TD4 HSE Santorini Black, 19" Alloys, Almond Leather, Lux Pack, Rear Spoiler, Adaptive Xenons

Hi Dave ,
Already checked the normal drain routes and are all clear
Andy

Yes, the small holes are drains, I think there are another two either side too. Sometimes they are hard to see as clogged.

Hi wizking, nice to meet you yesterday, always good to put a face to the name, been and had a prod with some weld rod, it appears to drain into the black cover with vents , but can't really see an exit for it , either way I'm not sure that this is the cause of my problem, but it's another possible cause discounted.
Andy

Yes, same here mate, and thanks again.
Wish I could help more with the misting problem, but I really can't think what is causing this.

Andy,

Have you got a sunroof? If so, could it be possible that water is getting in some where through here? I'm presuming it may have drainage channels or pipes running through the car somewhere????? Possible that one of these is blocked or disconnected? Same thing for the roof bar mounting positions, maybe water entering the interior through here?

Seeing as your post is nearly 4 pages long now and you seem to have investigated every possible cause, the above really is now pure guess work.

I really can understand your frustration with this. MY2010 TD4 HSE Santorini Black, 19" Alloys, Almond Leather, Lux Pack, Rear Spoiler, Adaptive Xenons

Hi Dave, no sunroof , so that's not a problem, car is completely dry, clears quite quickly but just is really annoying , on what's meant to be a quality car
Andy

Day off today, so another go at finding the cause of misting, took off battery cover and had a look at top right hand side under the black over and it was pretty damp, put some water down the screen and it was indeed dripping into this area , on closer inspection as wizking said there are two small drain holes in front of where the wiper would be on a lhd car, they were pretty blocked , so cleared these out and now water drains quickly away, is it possible that because the drain holes were blocked this was keeping this area moist/wet and then this moist air was being pulled into the car via the main inlet for ventilation which is just to the left of this bit? An hoping that now drains are clear that any water in this area will dry out quicker .
Hoping this is the cause but not holding my breath!
Andy

Had my car a year and never noticed those six drain holes before because they were blocked solid with black mud, flat blade screwdriver cleared them out though, so thanks for that.

Bit of a mission this thread, hope you sort it. 
Hung like Einstein, smart as a horse.

I looked at the holes on mine today. Never realised they were there. Car has just turned one year old and the passenger side ones were blocked. Gave them a gentle scrub with an old toothbrush and the puddle of water built up in the drain area gurgled away... something to check occasionally  2016 BMW X3 30d SE in red
MY2013 SD4 XS Firenze Red, 19" 10 spoke contrast paint wheels, Signature Strips, Grand Black Lacquer trim, Cold Climate Pack - gone!
2007 TD4 S Stornoway Grey - gone!

For what they charge youd have thought the service guys would check and clean them out for you wouldnt you?

I mean they put grease on the door locks so it gets on the wifes coat as she gets in.