Just to add some more fuel to the custom fire...
Didn't I read somwhere that at least one of the FE's had support for an input?
If the FE guys wouldn't mind writing code for it, it wouldn't be too hard to hook up a simple light sensor to automatically dim the display when it gets below a certain light threshold. I don't think the wiring would be too hard to do.
The first link I pulled off Google has a fairly basic circuit that could be used for this application.
http://www.uoguelph.ca/~antoon/circ/sensor2.htm
Anyway, maybe not worth the bother, a set time would probably suffice, but at least it'll dim when you pull into an underground or go through a tunnel. That, and the fact that it's just cool
Cheers,
Kris