So, you haven't seen the movie.
This cartoon is about character building, friendship, doing the right thing.. just like all Disney cartoons are. Just like the toys and the ants were stand-ins for people, so are the cars.
I saw the movie while stuck out of town for an evening. It's nicely done. You can call it nostalgic for the old days of cars, but you can also call it nostalgic for the old days of general friendliness and courtesy that used to prevail. (true or not).
Also, in a car culture kind of way, it is nostalgic for the days when your journey was part of your vacation, not something you had to get out of the way as quickly as possible. You can take it like that, or you can take it in the more general sense, life is something you enjoy along the way, not something to simply increase the speed of.
I believe it was Ghandi who said "there is more to life than increasing its speed" Cars has a lot of that notion in it.
The difference between Genius and Stupidity is that Genius has its limits.