Ok, I drove it...
My thoughts:
Seats - very comfy, driving position good. Visibility good. Nice big door mirrors - which are folding as standard it seems.
HUD is brilliant on the road
Parking sensors and camera are good - just as well given the usual car dealership car park chaos.
Ride is firm but not crashy - this was on stock 18's and no DCC. If anything its softer than my GTD on 18's with no DCC. We drove over lots of terrible road surfaces too.
It was wet but didn't feel skittish - I guess AWD does that.
MPG in normal drive mode and just doing normal stuff was impressive - I got 42mpg out of it over about 10 miles.
On the way back I then dropped into sport and then sport+...
In sport it was quick but smooth... it was pretty damned quick. A definite shove in the back when you boot it.
In sport+ the gear changes are harsh bangs, it holds the gears really long but oh boy does it fly. From a 40mph roll-on I overtook another car - was pushing 100mph by the time I'd got past him...
Braking into a roundabout I got exhaust pops and bangs

In Fred drives like a nutter mode it does 27mpg.
Didn't try flappy paddles as I'm not used to them and had a limited time to play.
It's a very impressive car. I think the 42mpg in normal mode is actually what is likely to sell it to me.
Now the only thing is can I stand not having Android Auto... I really need Waze with a licence loser like that...
In the end my probable spec was:
M135i
Paint (no idea which, they all cost the same unless you want white which is "free")
Tech Pack
ACC
Lumber support
comes to £39,675 - so sub the magic 40k.