Can cars in the Pixar Cars universe be immortal?

Question

Unlike humans, cars are made out of manufactured parts which are all (in the human world) replaceable and able to be manufactured. If you were completely committed to keeping a car, you could theoretically replace every single part.

How does this work in the Cars universe? If you replaced every part in a car, would it still be the old car or is there a piece that contains their intelligence, memories or soul that would be lost?

Follow up: What happens to cars when their manufacturers stop making replacement parts? Would there be some kind of battle royale as the last surviving cars of a particular brand stockpile the parts that will allow them to survive? (Kind of like how Wall-E cannibalizes parts from the other trash robots who have broken down)

Answer 1

What do we know about cars in the Cars universe? Well, for starters...

They're living creatures, living as in organic.

Q. In Cars 2, you mention the existence of dinosaurs. Are those dinosaurs flesh and blood or are they cars? And further, do you have to vet those sorts of references that may introduce a different aspect to the series’ mythology?

JL: I mean, in the mythology of the Cars world, the living creatures are vehicles of some kind, and so it’s like with dinosaurs. I always imagined it would be some kind of dinosaur-like car or vehicle, something like that. It would actually be an animal. And whether it would actually go down in the earth’s crust and get smushed and actually make a fossil fuel, I don’t know — we don’t go kind of that deep into the mythology of the world. - _{^{John Lasseter}}

Can a car's engine be upgraded?

Certainly they can. In Cars 2, Sir Miles allegedly guts his existing (diesel) engine and replaces it with a fancy electric one, powered by replacing his windows and roof with solar panels. No-one seems to think this is especially mind-blowing, albeit some people think he's a hippy for doing it.

Can a car's other (mechanical) parts be upgraded?

Yes, the parts that are most obviously replaceable are exterior elements; bumpers, engines, headlights, eyes, exhaust systems, etc etc. The only parts that seem integral are the bits inside the cab which presumably is where the organics are found.

So basically it's only the internal organs that can't be upgraded?

This is the nub. The filmmakers apparently gave some serious thought to where a car's brains and other organs are located, before ultimately giving up and settling for a strict rule of funny interpretation.

Interpretation #1 - The brains are found inside the driver's cab

vs.

Interpretation #2 - The engine is the brain

So are cars immortal?

No. We see multiple old cars, some of whom are very wealthy. If it was possible to do a full upgrade, there's no reason to assume that they wouldn't. Since the internal organs are, presumably prone to the same sort of aging as humans suffer then simply upgrading your machine elements wouldn't make you immortal.

Answer 2

Clues in the movie point to the cars having natural lifespans like human beings. The newer model cars like Lightning McQueen and Sally are voiced by younger actors and have younger personalities, while the older model cars like Doc Hudson and McQueen's Rust-Eze sponsors are voiced by older actors. Very old cars, like Lizzie the old Model-T, are almost nowhere to be seen, suggesting they have all but died out. And we know that Lizzie's husband Stanley, the founder of Radiator Springs, has passed on, suggesting that eventually the anthropomorphic cars do give up the ghost.

What specific parts of the cars contain their intelligence or emotions, who knows? Where do they even come from in the first place? Do they reproduce by themselves, or do they come from a factory? There are so many questions about the Cars universe that keep me up at night.