That's quite easy, any member on the (Cape)Whatsapp group can add you.
Then you mute the group.
Then you read the 100 + messages per day (often BS/cooking/other cars/part&cars for sale)
Someone will soon start organizing a get together, and normally a new group is created for that, so as not to overload the main group with(more) non-general chatter.
If you don't like it, you leave anytime.
I will add you, at your own risk.