I have discovered this. It is valid for FS9, FSX and P3dV2
But is specially interesting in P3DV2 where activating HDR the VC of some aircraft, becomes very dark, It can be improved as follows:
In the "panel.cfg" file there is a section called "Color", usually at the end.
Carenado Bonanza
[Color]
Day=255,255,255
Night=1,31,28
Luminous=255,255,255
"The plane you want to change"
[Color]
Day=255,255,255
Night=223,255,255
Luminous=246,115,119 <<<<<<< Some planes have values like this and the VC becomes very dark, I think that's the cause
Put all values as the default Bonanza: 255,255,255 (which i imagine 255 should be the maximum). Backup the panel.cfg or write the new values and just put // before the originals (this inhibits any value behind) .
That is:
"The plane you want to change"
[Color]
Day=255,255,255
Night=223,255,255
Luminous=255,255,255 //246,115,119