Haven't seen this one discussed but is very interesting data for these aeroshells, the velocity and vector figures on page 6 and 7 are easier to understand than the rest:
Experimental Investigation of the Near Wake of a Pick-up Truck
https://eprints.kfupm.edu.sa/453/1/2003_01_0651.pdf
The horizontal view shows some serious eddies forming from the sides of the bed too