hmm, until I see the screen I can't comment, but I know my handheld garmin screen auto dims at night so it isn't so bright. I assume it senses it and turns the maps to black so they aren't as bright. I am fairly certain my panasonic avic d3 even does that as well, but I would have to check it to be certain.
this is something dynavin should do for sure. they need to have auto dim at night. I don't think turning the screen off is needed, but dimming it or changing the color or something like your typical garmin units. Or, is that something with the software? Maybe try the garmin software and see if that auto dims.