1955 Porsche 550 RSK in an ivory white I came up with and black wheels.
1960 Porsche 718 RS 60. I didn't care for the original silver, so I switched to polished two-tone. Dark silver base with medium blue highlights. It wasn't so obvious at first, but I tinkered with it and I think it's really starting to pop now. Just look at it next to that Ferrari 250 GTO. Oh, and the wheels are painted dark gray (not quite black).
1973 Porsche 911 2.7 RS Carrera. I actually have two of them. White for roads and black for off-road.
2016 Porsche 918 Spyder (am I the only one who sees the word "spider/spyder" and hears Will Ferrell as Megamind saying "spee-ider"?) I gave it a basic Gulf livery color scheme and put it up on my storefront. Five downloads so far. I can assure you those colors are exact. I've done my research. You can read it here.
Loving the Forzathon events this month, the 959 is incredible to drive, spent most of my game time yesterday just tearing around in it without doing any events or getting anything done at all, just pleasure cruising.