Another degreed Mechanical Engineer here. Here's a video that helps support what ElSupreme is saying with regard to turbulent flow reducing "backfill" drag.
When the wing is flying normally, the pieces of yarn flow smoothly backward. This is laminar flow. The air tends to stay close to the contour of the wing, and the lower pressure above the wing contributes to lift.
As the pilot pitches the aircraft up, turbulent flow begins to get generated on the wing as the smooth airflow detaches from the surface (seen with the yarn starting to curve in different directions). This turbulent air above the wing increases the pressure there, reducing the amount of upward lifting force generated by the wing (hence a stall). In other words, the turbulence causes air to "backfill" above the wing and increase the pressure above it (lowering lift).
You want a similar thing to happen in a car--except in the case of a car, the turbulent "backfill" behind the car REDUCES drag, whereas with a wing it reduced lift. But as ElSupreme said, you want this to happen toward the back of the car (low pressure wake area), not the front.
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Side note of interest: you'll notice the wing root area (close to the fuselage) gets this turbulent airflow (and more of it) before the tip of the wing. This is due to wing "washout"--a design twist in the wing in which the wing is designed to be slightly more pitched up at the root than the tip. As a result, the root starts to stall before the wingtip. This is so that the pilot can detect the stall by feel (vibration of the buffeting turbulent air near the wing root) before roll control (obtained by the ailerons which are located at the tip of the wing) is lost.
Random fact. Fun to talk about at parties
