After some mostly unhelpful internet research, I reached out to BMW and was put in touch with President of BMW Designworks Oliver Heilmer. Designworks is a design shop wholly owned by BMW in LA, and it was intimately involved with the entire process that resulted in BMW's X family of SUVs. So it's appropriate that I'm speaking to Heilmer about the X4's dashboard.
Heilmer told me that BMW's characteristic orange-red hue is generated by light at a wavelength of 605 nanometers. The color was chosen to allow the driver to clearly see the instrument cluster, but also to be able to adjust to the darkness outside the vehicle quickly after looking up. The eye doesn't tire as quickly trying to read gauges illuminated with red-orange light, he said. BMW discovered this in the 1970s, and it's been both an aesthetic trademark and a conscious ergonomic decision ever since.
Heilmer explains that the new 5 and 7 Series cars use an intelligent system keyed to a windshield-mounted light sensor for more control of the light color and intensity presented to the driver. BMW has also conducted further research that's found less difference between white and orange-red light at night than previously thought, so these newer cars will maintain neutral white dial illumination even at night (at somewhat reduced intensity), with orange-red displayed less prominently. With fully programable and digital instruments, Heilmer says, "from BMW's point of view the ideal adjustment is always displayed accordingly."
So, if dashboard lighting can be resolved, perhaps a physics release could be the next priority, maybe, please ..............