Do you have a link ? I was not aware of that, the only thing I can find is that McLaren ran some tests to replace in-cockpit ads with a small eink screen, but nothing on the side of the cars.
also to clarify, I just called it "e-ink" because I didn't know what it was, it just looked like e-ink based on how it seems to change (flicker and then transition to new image). I have no idea what it is :D