A car acts like an (imperfect) airplane wing at speed-the pressure difference between the air flowing around the top of the car and the air going underneath can lift the car up. This is why you have airflow spoilers on the lip of the trunk of certain cars, and actual upside-down wings on struts on higher-performance ones.
But...those create drag, so there's diminishing returns in using them.
Another option is to disrupt or remove the air flowing under the car. This can be done by passive airflow redirection using an undercarriage tray, or actively via fans/blowers, or both.
F1 designer Gordon Murray famously developed a racecar using a fan duct (the '78 Brabham BT46) which did so well it was immediately banned. He later went on to do the McLaren F1 road car, as well as various recent GMA sports cars with this feature.
Now I understand more. But it surprises me that they did not explain it. Why do they not make a clear connection between the "show" and the real possible application in the real car?
Is this only a big Ad with a very far connection to reality?
"The "B" variant of the car, also known as the "fan car", was introduced at the 1978 Swedish Grand Prix as a counter to the dominant ground effect Lotus 79. The BT46B generated an immense amount of downforce utilizing a fan, claimed to be for increased cooling, but which also extracted air from beneath the car."
A car acts like an (imperfect) airplane wing at speed-the pressure difference between the air flowing around the top of the car and the air going underneath can lift the car up. This is why you have airflow spoilers on the lip of the trunk of certain cars, and actual upside-down wings on struts on higher-performance ones.
But...those create drag, so there's diminishing returns in using them. Another option is to disrupt or remove the air flowing under the car. This can be done by passive airflow redirection using an undercarriage tray, or actively via fans/blowers, or both.
F1 designer Gordon Murray famously developed a racecar using a fan duct (the '78 Brabham BT46) which did so well it was immediately banned. He later went on to do the McLaren F1 road car, as well as various recent GMA sports cars with this feature.
Now I understand more. But it surprises me that they did not explain it. Why do they not make a clear connection between the "show" and the real possible application in the real car?
Is this only a big Ad with a very far connection to reality?
It depends on the audience.
For 99% of drivers, serious active aerodynamic features are irrelevant. You'll never be driving fast enough for it make a difference.
For racers, it's a big deal.
See https://en.wikipedia.org/wiki/Downforce
When the fans and fins press you down you have more traction, so you can turn harder and faster without rolling or sliding
So, the Tesla demonstration is just to show that they can make the car more "stick" to the road and then go faster. Do I understand?
That's the practical purpose, faster cornering, faster takeoff. It's been tried before as well. For example a version of this car from 1978 Formula 1:
https://en.wikipedia.org/wiki/Brabham_BT46
"The "B" variant of the car, also known as the "fan car", was introduced at the 1978 Swedish Grand Prix as a counter to the dominant ground effect Lotus 79. The BT46B generated an immense amount of downforce utilizing a fan, claimed to be for increased cooling, but which also extracted air from beneath the car."