Fellas, I've got excelent news: a few days ago there was a breakthrough in NFSMW modding, now you can *add* cars to the game (as demostrated here with my Sentra SE-R mod, which has it's own vehicle entry).
A modder named MWInside developed some tools to allow you to add cars to the game with relative ease, the only caveat is that you should either create a new save file or patch a existing save with the tools he provides in order to use them. You can check out and download his tools here: https://www.youtube.com/watch?v=A6fhD4e3TSg&list=PLAoDduWz8eQkhvDq1jUdJ331OuL0VUtqu
If you want to try out a true addon car right now, nlgzrgn (the guy behind Extra Options for several games) made a addon version of Arushan's Ferrari 360 (the first NFSMW mod car). You can get it here: https://nfsmods.xyz/mod/694
(https://i.imgur.com/MAXdSy6.png)
That's pretty awesome!Nice work, MWInside!