Usual disclaimer: I am not a lawyer and in this site questions about these issues have to be always taken as ideas, thoughts or experiences, never as technical advice.
That said, yes, if you or somebody from the developer team wants to use the names of the cars, the names of the car companies or the models of the cars, a license will be needed. Otherwise, you risk having to face legal problems. Never forget that when sued, just the time and resources you will have to spend in the legal struggle will be harmful no matter the result. But even worse, at the end, without the licenses, you likely will loose all the work you and your team have put a lot of effort into preparing.
For the sake of detailing, keep in mind that car names and car manufacturer names are trademarked, while the assets representing the cars (i.e. the car models) are copyrighted. Trademarking and copyrighting are two different things: "Video Games and the law: Copyright, Trademark and Intellectual Property".
Lastly, of course if modders came up with car models, then that is not necessarily a legal problem for you. I mean not necessarily, because you have also to be careful of not endorsing mods that infringe copyrights or trademarks, in order to be sure that you are safe from legal problems. Although the mods are not your responsability, if your game's website for instance holds tons of mods that are considered to be illegal due to infringing copyrights/trademarks, I doubt it won't give you trouble.