I'm going to be very suspicious of a car sent to the crusher that fast. Process here is that the police keep the car as evidence until computers are downloaded, pictures taken, and systems are checked. It takes a lot more then a couple of days. In Texas, I believe this investigation is done by the Texas Rangers, unless in a large urban area that has the ability to do this.
Then the insurance comes and investigates. The insurance company wants to find someone else to blame so it doesn't have to pay. Then the junk yard goes to work on the car. Everything that can be salvaged is removed from the car. Junk yards don't work fast.
Two days? Two weeks if you're lucky normally and usually closer to two months or more.
Normally in a fatal, every piece of the car is picked up and sent to investigation. This is after the piece is photographed at the scene and documented. But since you have cops who either intentionally or accidently destroying the crime scene, here's what I'd do with this.
To get the type of accident you want, you need the tire to shred from decompression and lateral forces. In other words, losing air when being pushed to the side tends to cause a tire to break apart. The tire will end up in some large and a lot of small pieces. Your bullet needs to go through the tire, as it's going to be the exit wound that does most of the damage. Ideally you want a bullet that fragments.
Have him find a small piece of the sidewall where there is a fragment hole through the tire.
Shell casings and cigarette butts on the side of a Texas highway are probably the norm.
Best of luck,
Jim Clark-Dawe