I don't often drive my 230 at night, so i didn't notice, but i've just checked and the top left blue lever is much dimmer than the other three, i wonder if it's to do with the colour, perhaps it's denser, but i can't imagine why it would make such a difference, perhaps lots of cars suffer this. It's the same bulb and bulb holder that illuminates the bottom left and that one's bright, so makes no sense