Leon, to answer your question, I don't believe anyone has been sued yet over the use of the GT40 trademark, or body shape. The good folks at Superformance have licensed the right to use the term "GT40" from the folks who own the trademark. You'll notice other manufacturers of replica GT40s don't use the term "GT40" to describe their product. For good reason. They would get sued.
The owners of the GT40 trademark recently attempted to not only claim the written mark "GT40" as owned by them, but also the shape of the GT40 car. Yes, the shape. The reason for this was to then be able to extract a license fee from anyone making a GT40 replica (Tornado, CAV, RCR, etc.). That's not just idle talk. That's fact.
As usual, follow the money in these kind of matters and you'll find the answer.
Regarding ferrari replicas, that's not idle chat or speculation either. There has been a number of forced seizures of ferrari replicas in Europe, typically when the car is in transit and more easily seized by ferrari....or more precisely, customs authorities acting under court order at the behest of ferrari's team of intellectual property lawyers. Ferrari has successfully established that it not only owns the ferrari name, but also the very shape of all ferrari cars. Thus, anyone making ferrari replicas is quite exposed to having their work seized and sued.
Again, that's not idle chit chat, that's fact and reality.