I bought one a while ago as it was dead-cheap on eBay
I'd definitely recommend applying for the Beta here -
https://caristaapp.com/p/beta
Apparently you get far more options available to modify, and it enables all the features of the paid subscription model.
I've only done really silly things like add Trophy Mode, something called a "Courtesy Wipe" which does 1 extra wipe of the blades after a screenwash, added an audible tone when I lock and unlock the car, and enabled Green Screen on the HMI
One thing I really wanted to enable was a feature where the windows close if the car is locked with windows down and rain is detected, but after much testing it turns out it's not available on my model because the rain-sensor turns off when locked, something that I believe changed on later models.
