You seem to be having a look at a rough batch of 166s.
Your silver one seems to have some issues that could possibly be down to over exposure to heat - Left sitting in direct sunlight constantly!?, not a problem in Scortland! The strange sticky effect on your interior and the door seal issues point to this in my opinion.
The scuttle shake is surely down to worn bushes - can make the 166 "skittish" especialy at the rear. The high density urethane injection sounds like a strange option to me that will have little effect.
Dougie - I was just 'on my way' to reply to your message in the other thread, with a link to this thread!
But you beat me.
You're right about the interior degradation, I reckon.
The creaking from the door seals is a symptom not a cause, and I get the distinct impression that it's because my car bends/twists in the middle. I can appreciate that the wayward handling will be fixed by replacement bushes (esp. at the rear) but I don't think this will do much for the rigidity problem - this would only go away if the suspension were much softer and therefore passed less of the shock into the structure. I suppose it's possible that the older car had softer damping?
I remember that my 164 had foam injected in the pillars (in the factory) and I think they did it for this reason. I did some Google searches and picked up on a few cases where manufacturers (Nissan/Infinity) and enthusiasts (SCC Magazine in the USA and their Nissan 300ZX project car) have done something similar. I imagine that when you fill a steel box section with something difficult-to-compress, you increase the force required to twist or bend the box section.
To summarise many sites, here's one forum: Chassis strenghtening and soundproofing - foaming - Bimmerforums - The Ultimate BMW Forum
Obviously there are a number of people who have thought of this, but it's all somewhat mystical because for every person that says it has a structural benefit, there is someone else who says that it's for sound-deadening. It could have something to do with the fact that the foam possibilities range from '2Lb' to '16Lb' - 2Lb has 35psi strength, 16Lb has over 700psi strength... obviously, the 16Lb is much more likely to have a strengthening effect. I'm getting this from the Urethane Foam , Expanding Marine Polyurethane Foam
EDIT: I just found Chassis stiffening foam result - Part 1, qualitative result*long post 56k go away* [Archive] - FreshAlloy.com Forums
which adds a lot more credence to the theory, thanks to some excerpts from manufacturer testing: http://photos.freshalloy.com/gallery...creenshot2.jpg
Relevant quote: "The most sensitive area of the body were found to be the A-pillar, the D-pillar and their joints. With structural foam injected into this sensitive areas, the vehicle body was significantly stiffened, as shown by the increase in modal frequencies."
So, when I've been looking for evidence of repairs to the floor, I've actually missed the more likely cause: possible repairs to the roof or roof pillars. And, the corollary is that the foam injected to the windscreen pillars of my 164 could indeed have a noticeable stiffening effect.
Anyway - will be interesting to see if anyone else has 'rigidity' issues or experiences with their 166. Not to be read in the wrong way, of course