Both our 'moderns' are Saabs and they do have a 'Night Panel' switch that turns all the dash lights off except for the 0 to 70 section of the speedometer. I'm told, by someone who has done it, that the rest of the speedo illuminates too if you go over 70.
However, if the car thinks that there is anything else you should know about it will illuminate that gauge as well, low fuel for example. And yes, it really makes night driving more pleasant.
All delightfully quirky, like our Triumphs.
Adrian