It is actually very close in ModDev whe nusing LochDrummond. It is probably more different depending on content used, not every track makes cars look equally well. It is more of an issue that setting shading in 3DsimED doesn't provide best idea how car will look in game.
I think I agree about the paint shader being too reflective, it might be slightly too strong and masking the true color a little too much. It does depend on view angle, sun angle and specularity, sky coverage... there can be less reflection and more color sometimes, can't make full judgement from pics. Although I personally like stronger reflections on cars. Looks more realistic to me, although of course there are all kinds of paints IRL. One thing I must say about rF2 shaders, to me they comes up looking a lot more natural and nicer than they does in AC. And then they works well in all lighting conditions - sunny, cloudy, dark... can't say that about AC, which is now probably modded so much and can get better, but probably needs adjsuting graphics sliders each time... I wish rF2 was a lot less jaggy.
The cars reflectivity will be very adjustable by liveries alpha channel. Not necessary to setup shader very precisely. Right now I have only two cars for initial release. Peach and Black. I have darkened alpha channel for both cars from complete white, to slight grey taint for peach car, and a bit darker alpha for black car, as dark colors are more reflective by themselves.