I used to believe that if you were moving at 20 miles an hour and wanted to go at 30 you had to briefly go at 40mph to fill in the gap.
i.e. 30mph - 20mph = 10 too little, if you travel at 40mph you have an extra 10 mph to spare which will fill the gap between 20 and 30 and so it would all even out at 30.
I know... I know... physics just wasn't my thing!
A childhood belief about cars

others believed things like this
- I thought the name Phillip was actually spelled "Fill Up"— Natasha H
- I thought when you get married you have to fill out a form to get a baby and then you get one.— Danielle
- I used to think that my mom had to buy ice cubes from the store and bring them home to fill up the trays.— Shawna
- i used to think that if you didint pick your nose it would fill up with bugers and youd suficate.— still havent broken the habit bob
- I thought God drove a car like ours - a Honda. The song DID say "fill the heavens with sweet Accords..."— Dummy
- When I was about 4 and I saw the clouds moving sideways, I thought that Earth was moving closer to the Sun— Helen