Diet:

Realistically speaking, if we were to talk about gas and oil when it comes to cars, gas would be the food, and oil would be the blood. But that's not the case in the Cars franchise. In cars, they are seen drinking oil out of cans. This means the oil is the food source since it's being ingested through the mouth. But, simultaneously, the cars also fill up gas through their gas cap to refill energy. So does that mean they have two mouth holes that lead to the stomach? Could gas and oil both be food sources that are ingested differently and serve different "nutrients" for the cars? In the first film, though, a line of dialogue from a car says, "My oil pressure is through the roof." So, if cars get oil changes, is that a stomach pump, juice cleanse, and a blood transfusion simultaneously? But if oil really is the blood, then why does Mater mention that vampires siphon gas out of you in Cars 2? Isn't oil supposed to be blood? When McQueen tries to drive away from radiator's springs but fails due to running out of gas, Sally and the sheriff reveal that they have siphoned his gas while he was unconscious. That means that they sucked out his food/blood from his stomach while he was unconscious. What about the excretory systems? We see them have oil leaks before, and it's seen as an embarrassment or shameful. Something that only elderly or broken-down cars do. The only thing that makes sense to me is that oil in the car universe is like water; cars drink it to stay hydrated or lubricated for their body parts to move without friction, but if there's an access amount of oil, they'd either leak or pee it out. As for gas, that would be the energy source they need to drive, so it's food and acts as fuel. Maybe for cars, pee, blood, and water are bodily fluids that are simultaneous to their bodies. I don't know how the oil wouldn't damage their teeth. Are the cars just wearing veneers? Or is their tooth enamel able to withstand oil and gas? Why would they even need teeth? They don't chew on anything. They drink.