All Credit goes to Hansel22 over at RFactor Central for the skins. All I did was change the Alpha Layer of the textures, since the base was too shiny.
If he opposes me uploading the skins here, I'll obviously take them down.
I converted them over a year ago and just now decided to upload the skins. Keep in mind that I made the conversion rather bluntly and over a year ago, meaning that the shiny/matte-ness may be a bit off, so let me know if something seems weird to you and I may be bothered to take another look at them.
I don't know the first thing about creating custom textures, so this will probably be the end of the line for me. Might be 'neat' if there was a streamlined way to make these skins accessible to F_Extreme and/or F_Ultimate, but that is beyond me, at least for now. Maybe somebody else might take a crack at it.
I think these skins are loosely based on the ~2010 - or so season, but I'm sure there's something for anyone.
Check out the link (Warning: It's RfactorCentral. My browser noted the link was unsafe, but it should be fine...) if you're interested in seeing pictures.
Extract the package so that you have a folder called F_Reiza, in which you have all other folders, which contain the driver-specific Textures and Veh.-Files. Drag and drop that F_Reiza Folder into your AMS/Gamedata/Vehicles folder.
In AMS, the Vehicles should be visible in the Formula Reiza series, and under All Cars & Tracks.