Kelly's statement above is well said, but not particularly accurate. Porsche owns, or claims to own, the rights to use many names associated with the marque, including, for our purposes, Porsche and Speedster. They also own, or claim to own, the distinctive shapes of models 356, 911, etc. Porsche has allowed the replica market to exist by not enforcing the above trade name, trade dress, and shape ownership rights.
We should all be aware that Porsche has the right to enforce their claims against anyone that they assert is infringing on their copyright claims. This includes individual car owners, businesses, etc. Of course, reality raises many concerns regarding enforcement, including unfavorable PR that would ensue and the impracticality of the defendant class size. It's just not practical or economically feasible to try to enforce such claims against an unknown class of defendants that may number 10,000-15,000.
So, from a practical viewpoint, Kelly is correct that Porsche is unlikely to attempt enforcement at the level of individual car owners. Moreover, that lack of enforcement may be one of Porsche's problems if they ever did try to enforce copyright claims on an individual level, as the court may find that Porsche's benign neglect allowed the aftermarket to grow, and they have now lost enforcement rights due to such neglect over an extended time period. However, it is inaccurate to say that we are allowed to use Porsche scripts and shapes because we are private owners, and aren't making a profit from them.
None of us are privy to Porsche's internal posture on the issue of copyright claims. Will other businesses receive letters like JPS? Unknown at this time. One thing is pretty certain, though. The more replicas driving around with Porsche emblems on them, the more likely Porsche is to take action. Can we, as replica owners, anticipate a JPS letter in our mailbox? Almost certainly not.
The accepted legal fiction that individual owners are mounting Porsche scripts, not businesses, would have little effect on the trier of fact's opinion in a case of copyright infringement. It is usually unwise to wave the red flag in the bull's face.
Bill, You make it sound as if JPS had lots of choices in this matter. His practical choices were two: 1) do what Porsche says or 2) go to court. He agreed to do what Porsche told him to do. In his situation, I would have done the same.