I'm with BB.
the night panel on my 93SC was great, especially on long unlit A-road or motorway runs. All the buttons stayed illuminated, but the distracting LCDs (heating, stereo dash top 'info display') and dials (except speedo) went off, unless they had something to tell you!
Put some soothing music on and with the soft green lighting you could be asleep in minutes...hmmm
The 159 one is dissapointingly poor in comparison...from memory I don't think it even turns off the bright red LCD info panel between the main dials, hence i never really bother with it. But, it was the same with the 147 'night panel' which I had before the SAAB, so I wasn't surprised!