I wrote a rather lengthy post on this topic - but I didn't have your casings details.
So, the "truck" had to be stopped or nearly so, for that to happen. And if back driver's side, then shots were fired from passenger's side of the truck (meaning that unless the driver is actually shooting past his own passenger's head that only one person fired. At any rate, had to be going slo-o-oowly in order for the casings to all be at the back driver's side (I realize that it would only take seconds for this to happen - gun firing quickly, truck driving very slowly, or stopped).
No bullets hitting the vehicle (and therefore being found) is absolutely amazing. These two crooks are the worst shots ever. They must have pulled up alongside, fired 7-10 rounds (one of them did), and only managed to graze his scalp or something.
Wow. Anyway, I need to revise my post.
I hope they're out there with a metal detector - bullets must be close by (unless all of them somehow flew over the car - so that Mr. Murdaugh surely must have stood up between the car and the truck as he attempted to flee.
How lucky for him.