You are right - Elon might be using actual thrusters that can push and corner a two tonne car but I also think that you are right to guess that that solution might not be road legal.
My bet is still for suction using an air curtain rather than small directed nozzles. In the last month or two I redid the estimates and I got about 400 mph for the speed of the air in the curtain. Pebbles that were thrown up would not break your skin (surprisingly).
(PS I have assumed 10,000 psi because that was a figure that Elon used in an interview. My earlier calculations used 5,000 psi but it turned out that 'ordinary'/typical was not good enough for SpaceX!)
My bet is still for suction using an air curtain rather than small directed nozzles. In the last month or two I redid the estimates and I got about 400 mph for the speed of the air in the curtain. Pebbles that were thrown up would not break your skin (surprisingly).
(PS I have assumed 10,000 psi because that was a figure that Elon used in an interview. My earlier calculations used 5,000 psi but it turned out that 'ordinary'/typical was not good enough for SpaceX!)