The stock dome light in the Z3 M Roadster is very dim, almost to the point of being useless. Long ago I designed a PCB to hold Luxeon K2 LED emitters, and it became my dome light. It was much brighter, with separate control for red/orange lighting.

When the Luxeon K2 became unavailable, I designed a new setup using Luxeon Rebels. This one is very bright, and has a dimming facility as well as the red/orange control.