Since firstname.lastname@example.org couldn’t be bothered, I decided to post these myself on Oppo.
Both the Kia Soul and the Chevy (rental, probably) were with the mules.
My personal opinion is that if a car company wants to test their cars inconspicuously, then they should probably avoid doing it near national parks (where there are plenty of tourists with cameras). This example was near Bryce Canyon. Land Rover has been known to patron Pikes Peak in the past.