I had a blown bulb in my dash cluster, so replaced it. I discovered that the original bulbs that backlight the gauges have this green condom on them as a filter. I replaced all the bulbs (seeing as how they probably had all been there for 20 years/335K km and it's a major PITA to get my stubby fingers in behind there to unhook the speedo cable), no filters; the difference in brightness is amazing. The dimmer actually has a purpose, now.
I replaced the bulbs in my heater controls as well; didn't even know they were normally illuminated!
I replaced the bulbs in my heater controls as well; didn't even know they were normally illuminated!