The dealer did a bump and run knowing a prepurchase inspection would blow up the deal.

I bought a really nice 996TT from a guy who had it on ebay.

Any used car transaction of any kind requires due diligence. The worst car deal I ever did was buying a BMW from my dentist who was also my friend. I trusted him and did not check the car and bought it at night.
It had been wrecked and had a total repaint.

 

The more the dealer maneuvers to avoid the PPI (and they are often slick about it) the more important it is to insist on it.

Save yourself some time by telling the dealer during your first conversation that you are getting a PPI regardless of any circumstances.

Once I had an ebay dealer drop off a car at a Porsche dealer for the PPI... imagine the seller's surprise when the "inspector found evidence of major front-end paint work!" Afterwards, I called the inspector directly, who said the car was never dropped off for the inspection.

I declined to buy the car, and the dealer returned my deposit.

(The dealer referred to is neither in MO nor in my home state of NY).