Don't try this at home without the right knowledge!!!
It seems possible to select your own colors for attributes like roads in Mapsource and load these colors also in your GPS.
A Swedish member of the UKGSer forum shows in this threat an example of how road colors of Mapsource can be changed to the colors of the German Hallway AG maps. Its not yet 100%, because dirt roads are showed as normal roads and water is not showed as well.
Some Garmin units, i e 278 and 60CX, shows brown roads on brown background:
One problem is that all lakes disappear with the updated road graphics. Solution is to show the roads from the modified CNEv10 overlaid on the CNEv9 map.
This is how to do it:
1. Install City Navigator Europe 2008 (CNEv10) in Mapsource. Assume that this map is stored in C:\Garmin\CNEURO10
2. Download hallwag.typ and put it in C:\Garmin\CNEURO10
3. Add a pointer to the new typ-file to the Registry. It should look something like this (don't tamper with the Registry if you don't know what you are doing!)
[HKEY_LOCAL_MACHINE\SOFTWARE\Garmin\Mapsource\FamiliesNT\City Navigator Europe NT 2008]
4. If your GPS has CNEv9 preinstalled then upload with Mapsource new map segment from the re-typed CNEv10 to your memory card.
If your GPS has no preinstalled map, upload with Mapsource map segments from both CNEv9 (or CNEv8) and the re-typed CNEv10 to your GPS.
5. Activate, in the GPS, both maps.
If you like to try this yourself or repeat this to get your own colors, i don't know yet, but then you need the program cGPSmapper and you can use the manual: Creating DEM-like maps using TYP customisation. The nüvi is used in the examples.
Concluded: only for experts and still a lot of research needed before we can automate this. But maybe it is possible with this method to create our own map colors like the one's on Michelin, Falkplan, ... maps or even TomTom screen colors