Carsick - meant that the car was sick and would throw up
One set of keys could operate every car in the world, and if you lost your keys, you could use someone elses.
When playing with Lego/Matchbox cars, opening all doors made the cars have wings and fly
Carpool - A pool for cars
The glove compartment has gloves in it (seriously, has anyone ever kept gloves in there?)
A childhood belief about cars

others believed things like this
- When I was a kid I used to think the "carpool lane" was an actual pool cars went swimming in— skeez
- I used to believe that God was the one playing "cars" with our cars. Sounds weird hey?— Roe
- I thought the no overtaking sign meant that red cars cannot drive by black cars.— Helen
- I used to believe that weasels routinely nested in the glove compartments of cars.— Ven
- I thought small cars grew up to become big cars— carhugger
- I thought that people were like cars because cars have exhaust pipes, and people fart.— Matt