Having finished off (well, almost) the exterior trim above I got to work on the interior trim.
'Cos I like to support my local manufacturing (of which there is near-as-none left) I added to my trim refresh products, basically another bottle "Vinyl Care" from the same Aussie manufacturer which is designed for the interior rather than exterior trim:

The process is similar to the exterior, clean with the "Sublime Clean" and then use the "Vinyl Care." The areas I treated were the dashboard top, cluster, vent and centre console surrounds, steering wheel, door handles, levers, door trims (plastic not fabric), some switches (e.g. electric windows) and plastic sill plates. I was careful with the switchgear lest the product remove the switchgear labels- an issue I have had previously with other products. I used the steering wheel as the "litmus test" for ny residues.
The "Vinyl Care" again claims to be non-silicone, non-greasy and won't harm most anything. I'm pleased to report that is the case- no residue seemingly on anything, no harm to the switchgear or surfaces nor seemingly any nasty impregnation or dissolution of the surface. The results are also (mostly) very good, see photos below.
BUT (rant on)...the smell- not fragrance!. It's that sickly-sweet nauseating bubble-gum smell we all remember from our childhood that vaguely reminds you of spew. Memories com flooding back...
Sticky-yukky bubblegum under the desk?
Yep.
That awful feeling squishy feeling and you realise you've just stepped on semi-liquid bubble gum on hot tar and now you need to spend minutes cleaning it off?
You got it.
That slightly nauseating feeling in your stomach that half reminds you of spewing after eating too many lollies at a birthday party (Slightly??? Did I say slightly???!!).
UUUUGGGHHH!
You'd almost not buy the product again because of the bad smell memories, in spite of the results. Luckily it doesn't linger in/on the trim.
GET RID OF THE PONG, BOWDEN'S!!! (And that's not just done to prove I'm not some corporate lackey)
(rant off)
Ahem...Where was I? Oh yes, the results...
Well I didn't take a photo of the dashboard top because, well, there wasn't much difference to it at all. It remained a dull rather aged&dry looking matte grey. I suspect it may have been the victim of some previous application of an inferior product.
Now the rest of it went well. In fact, better than I expected. In particular, this product works very well on "hard" plastics. The black plastic centre-console and cluster surrounds were the best, followed by handles, switchgear, scuff plates, interior mouldings and door trim.
Here's a before&after (half/half) example of the cluster surround. Note the product needs to be applied in cool/shady conditions (i.e. not with the dash baking in the sun...not unreasonable really)
so the photo was taken inside and is slightly difficult to see, I've enhanced the brightness/contrast and I think you get the idea. Treated left, untreated right.

Only when you get the car out in the sunlight does the effectiveness become really apparent. Even without a before&after photo comparison you can see the effect.

The slight mottling on the steering wheel is probably due to my non-even application in the semi-dark, perhaps a flash effect coupled with plastic patterning...and the fact the horn is extremely touchy and went off all the time whilst restoring!

Dash really looks nice now, black parts almost look new.

Cheers,
Patrick