Car project never work no matter what you do. Many people in my family tried using diff bottles and using exact same instructions but the car never moves. Not sure if the video shows real work.
I failed to move the car at first, so what needed to improve is 1) There should be a distance between the bottom of bottle and the fan so there woulf be sufficient airflow to push the car forward 2) The tyre need to be at both end sonthe car would be more stable 3) The fan blade need to be twisted so it can gather some wind