There's two COMMON shades of black for BMWs-
- 475 which is your 335's Black Sapphire Metallic, and there's also...
- 668 (named Swartz2... German for Black2)

There's actually more but these are the 2 common ones. I want to say that you're right about your X5 being 475, as I do not recall seeing any X5s with 668 (but not saying they do not exist). Definitely put in the VIN on an online decoder as was recommended earlier!