Should not make any difference in letting new C8s sitting out in the weather
Keep in mind, water can get through the venting around the glass of the rear hatch
I'll let others more familiar with IAM answer if they wish, but if I recall, they only have space for 2 or 3 cars inside in total (excluding workshops, which I haven't seen). It isn't overly large inside. There is almost zero visitor parking, I parked on the street last time.
As for how we're treated (presumably by GM) in the UK, my first notice of my new car's arrival was when it was at the dealer, even though it likely spent weeks getting there from the US. It is also the first dealer I've ever been in that HASN'T offered any finance on a vehicle, which is usually where a lot of money is made by manufacturers.
It really isn't the setup you think it is. I'm not complaining about the simple nature of the dealership, as it is secondary to the car for me (and I don't need to sip a latte while discussing a car), but I do value good customer service/communication which costs nothing but time.
