To me, the most interesting aspect of the case is that his body was dumped in a fairly remote spot in dense vegetation that effectively delayed discovery (which isn’t unusual) but the vehicle was a abandoned fairy nearby the body dump site; which is unusual. Significantly, the vehicle was not close enough to the body to assist Law Enforcement in finding the body. That suggests the perpetrator was anxious to get rid of the car.
In an abduction/murder case where the victim’s vehicle is used, the location the vehicle is abandoned is very significant. If the car was abandoned near the abduction site, it suggests the perpetrator used it to return to his own vehicle or residence. If it is abandoned anywhere else, that would suggest they either lived near where the vehicle was abandoned or they had alternative transportation; someone to give them a ride (perhaps an accomplice) or public transportation (was Lyft and Uber checked).
If it was a random criminal, willing to commit a violent robbery or a murder for whatever cash was in the wallet of some opportunistic target, the perpetrator would have had some reason to be at the abduction site and that would be near their home or “base of operations”. If they did decide to travel any distance to dispose of the body, they would use that vehicle to return. Even with the victim’s vehicle, driving 15 miles to dispose of the body, would be unusual. There are always exceptions and unusual circumstances that could explain unpredicted behavior, but I suspect there was a second driver that followed the Porsche to the dump site and transported the perpetrator away. This was probably not a “random street crime”.
Incidentally, apparently Alan filled his tank at the gas station. If he was abducted and driven directly to the dump site, his tank should have been down about 1/2 gallon. If any more was used, that raises a lot of questions. Do we know how much gas was used.