I think I've finally found a video of the 18/19 in action (Black M4 starting at 1:19).
I'm contemplating whether to get the car with 18/19 or the 19/20. The streets of HK can be jarring and for a daily driver (only car) I'm still wondering if I want 19/20.
On the other hand 18x9.5" with 275/40 tires and 19x10.5" with 285/35 tires does sound pretty awesome for a Stock wheel/tire combo