To me it sounds OK. The 100$ question is : do the authors of the original meshes authorized derivative work ?
That's a question I (almost) always ask when someone post here blueprints made from a mesh ripped from a commercial game. When ripping the mesh, that someone is probably doing something illegal, but that don't concerns SMCars at this point. What concerns SMCars, is the posting here of a blueprint from the mesh: it's clearly a derivative work, and it's prohibited if the game authors didn't authorize derivate work. And usually, they don't.
I don't know the english word for that, but in french it's called "recel de contrefaçon" (online automated translator says "concealment of counterfeit")