I don't think you'll get the plate from that image. The detail just isn't going to be there. Looks to me like the right rear tire might be a compact spare (aka donut), which might also explain the incidental contact.
You might canvas the local businesses yourself to see if they have cameras pointed at the road, and do it quickly--they may not keep the footage that long. You can always direct the detective to the businesses that have evidence--PDs typically have more things to investigate than time to do it, and tracking down a no-injury accident can be time consuming and not their top priority.
The downside here is that you don't have footage of this car actually doing the damage. Hopefully you can find that in your search as it will count for evidence. If they can track down the car and find damage consistent with what you describe, you might get somewhere. Who knows if they can put an alert at body shops? Hopefully you can get some justice.