Based on
THIS it really seems like their main concern is ripping content from competitor's games and not so much the use of the brand/logo/image of companies. As long as Kunos isn't directly profiting from it, I'd guess most manufacturer's wouldn't mind a bit of free advertising. But I could certainly see other game developers getting rather cross if the cars/tracks they worked so hard to model suddenly show up in another game without permission, even if nobody is profiting from it.
This may not be a perfect analogy, but look at it like this: I own a restaurant that serves a very, very delicious
steak. If the owner of another restaurant wears a t-shirt with my logo on it I probably wouldn't have much problem with that as it would be free advertising to clientele who are obviously in the market for my services/products. But, if they bought one of my delicious
steaks and then served it in their restaurant and claimed it as their own, I'd have a problem with this and so would the law. Again, probably not a perfect analogy, but that's kind of the way I interpret it.