It seems to me that the mechanics of the investments in paintings and cars it is not used currently too often by players. I decided that in the next version I will give you more reasons to use it. Well, you can give gifts in the form of cars or paintings. Who will you be able to give them and for what?
Well, you can give gifts to all creators. For what? to improve your relationships with them. A kind gift is always good for the recipient;). Of course, more valuable gifts will be nicer to see (ie, giving a painting will significantly improve your relationship with a given creator than even the most busted car.) On the other hand, there will be some limits on which handing gifts will not improve your relationship – in the end, you cannot buy true friendship.
About why the relationships with the creators are important and what they affect in the game world you could read here.