(Warning: This is not the tire slasher (HEYO) movie you think it will be. I promise, it's much better.)
There are films that are extremely aware of themselves (See Kaufman/Jonze's
Adaptation), but probably not as aware as
Rubber, and possibly not in the way you would expect. With the premise it has (a tire with psychic powers that can blow up things: rusty cans, rabbits, and especially (Oh man...definitely) people's heads, it's extreme self-awareness is possibly the only way it could go.

Some commentary from "Rubber" OH GOD SO HUNGRYYY
However, it's self-awareness is not the "Yo man, a tire with psychic powers! That's crazy guys! Isn't this just hilarious!?" type. "Rubber" KNOWS it is a movie and knows that there is a real human being behind a screen watching it, and constantly plays with the relationship between film and audience, filmmaker and critic, and even different films with each other.
There are very clever ways "Rubber" does this. For instance, the very first shot is of a well dressed man standing on a desert road which has several black chairs placed randomly on it. A car comes into view and slowly tips over every chair, and comes to a stop while a cop pops out of the trunk. The cop has a glass of water and walks and faces the camera. He asks: "In Spielberg's "E.T.", why was the alien brown? No reason. In a romance film, why do the two people fall in love? No reason. In "The Pianist", the Polanski film, why did the guy have to hide and look like a bum when he was such a good piano player? No reason. This film is an homage to this No Reason." The camera then reveals that he is talking to an audience in the desert, and each member is handed a pair of binoculars and is told the film is being shown behind them. Another example is the same cop asking to be shot because "Hey, this isn't real! Shoot me! I won't feel a thing!"

Why are there chairs here? No reason.
"Rubber" is very good at asking questions such as "What happens to characters when they aren't being viewed?" and "What does entertainment really provide us?" and they way it presents and answers these questions are immensely clever, extremely funny, and the main charm.
From thinking "Rubber" would be a simple, ridiculous romp with zero thought and needless gore, it was surprising to find that instead it showed to be a very thought provoking and strange experience that ultimately DOES have reason.

SPOILER ALERT