I'm not saying it was a production-ready car, but the notion of it being styrofoam is stupid. These demos are as much for the morale of the engineers as they are for the entertainment of the public. Tesla doesn't need to demonstrate a rocket car.

Is it really so unbelievable that a car company with access to rocket engineers, built a car with rocket engines?

I read that the car used in the demo was actually a hundreds of kilograms, nothing like the real cars weight of ~ 2 ton

I believe he also made his own career disappear.

Just be aware you're moving from the territory of reasonable questions to moderately desperate conspiracy theory. Whatever it is we saw, it's clearly not lightweight. That much is obvious from the kinetics.