Your best bet is probably to try and arrange a visit to the BMW Classics Collection museum in Munich. Not 100% sure how one does that, but more than a few people have gotten to visit in recent years so it doesn't seem quite as impossible as it used to.
If you can't arrange a visit then perhaps they can give you information on its next planned outing.
Sadly BMW's press release for this latest appearance referred to the car as a "McLaren F1 STR" so if someone was searching for McLaren news they might have missed it depending on their search criteria.
>8^)
ER