Why are all the animals cars, but all the plants are still plants? Wouldn't the constant burning of fossil fuels mean that no plants can grow?
They mention Old Yeller in the Planes movie. What is the car equivalent of a dog? A motorcycle, maybe?
Cars 2 mentions that oil is a fossil fuel that came from dinosaurs. This raises so many more questions. Were the dinosaurs cars too? If so, what type of fuel did they run on? The Dinoco logo just shows a regular dinosaur, not a car one.
The villains of Cars 2 are "lemons" who are sick of society making fun of them. Don't the villains technically have a point? Isn't that ableism?
What if Lightning McQueen never wanted to be a race car? Is Cars a caste society in which you are born into your role? Or is there a way for you to change your species? Would that be considered cultural appropriation? Or would it be like being transgender?

All the cars are real-life makes and models, but what does that mean for the people those brands were named after? Was the car version of Henry Ford the first of his species? Are all other Fords his descendants? If two Fords had sex, would that be incest?
If there was a car Holocaust and car slavery, was there also a car Trail of Tears?
Does the Cars version of Hollywood have the same problem with whitewashing as the human Hollywood? Like, is there a bus actor that plays a plane character and gets canceled online for it?
Why do the cars all have doors and windows if there are no passengers inside them?
There's a statue of Stanley, the founder of Radiator Springs. How did they carve that statue?
Did car Elon Musk launch himself into space? Follow-up question: are rockets and satellites alive in the Cars universe?

Do cars have theme parks? Are the rides alive too?
They eat sushi in Cars 2, which implies that there exist fish. They also have ice cream, which means they have cows. But the cows in the Cars universe are tractors, so how do you get milk from a tractor?
Do the Fast and the Furious movies exist in the Cars universe? And if so, would they be R-rated for gratuitous car violence?
There's a car Queen Elizabeth II. Was there a car Princess Diana? Was her death a suicide?
If a car Jesus did exist, what miracles did he perform? Did he turn water into motor oil? How do you crucify a car? Was there also a car Moses, or a car Buddha?