Humster 3D claim to have their cars in Corona materials, I haven't had the chance to check it yet. So it would be nice to get some feedback, if you get to download it before me. :-)
Good luck in your search, looking forward to hear your result.
In general I miss a set of cars with a consistent setup, layer wise, material wise, so that it easily could be set in programs like RailClone - and it the materials was in Corona format, then it for sure would be an extra bonus
