Vent works just fine, can't turn it obviously as the innards are all removed, but airflow is perfectly ok still!
I'd prefer to have trimmed them down a bit, to sort off put them further back into the dash, but doubt i could get a nice smooth finish on the plastic. All blocked off solutions I've seen look wrong and cheap :/ Guess a 60mm gauge would fit a lot better in such a setup?
Edit: I'd prefer a a-pillar install like Damo's, but wont pass MOT here in Denmark with anything even remotely in the field of view....