If anyone wants to take a crack at these questions, feel free to do so.
1. Automotive;
downwash is always the result of a vortex, yes, no, maybe.
2. Automotive;
downwash is the byproduct of a sudden pressure change via air detachment, yes, no maybe.
I tried to do an image research on "Vortex Downwash" but only aircraft stuff came up.
Then I did a image search on "Automobile Downwash" and found the below.
2011-04-12
The New Audi A6/A7 Family - Aerodynamic Development of Different Body Types on One Platform 2011-01-0175
https://www.sae.org/publications/tec.../2011-01-0175/