[Burrcold]

I wouldn't worry about it. BMW "Chalk" is going to be close to or identical to the Porsche Chalk. The thing with Chalk is that it looks very different on almost every car, even within the Porsche lineup. Here is a Cayman and a Cayenne both in Chalk. One looks darker with a more brownish warm hue, whereas the Cayman is lighter with a more white/bluish hue.

If you like the color, just get it! It will be close enough that you will not notice the difference (probably even next to a Chalk colored Porsche).

I've noticed the same variances with Audi's "Nardo Grey" (which is what I had on both my RS5's). A friend of mine had an M340i in Nardo Grey, and to me it looked much different but in reality it wasn't. It was just the car, the lines, the lighting, etc. etc.