[Seahawk]

My company deals with this all the time...and we have a "guy who knows a guy" because the downside of IP/Data Rights/Patent infringement dwarfs the upside unless you are careful.

There are specific things that garner IP and a Patent, none of them have anything to do with a specific vehicle or shape, none...you can't Patent an airplane or a car but you can Patent a wing design for an airplane or an application for a car...

In my companies world, UAS, we have a unique set of designs we developed for the commercial UAS/drone market. What we own, the IP, is our control software...nothing else matters in our community. We also have, and this is important, proprietary rights for other software applications we developed, which we jealously guard.

For the Department of Defense we like to pursuit Small Business Innovative Research (SBIR) projects because the the government assigns data rights under the SBIR and other companies much larger than mine can't use the data and designs we produced under the SBIR contract to compete with us. A big deal.

All that said, to your questions:

-Can you replicate one-off concept cars legally? Yes, just do not do an exact replica of the design and do due diligence on any particular design artifacts that may be IP related: Don't include an item that the OEM still feels they own. That is where the Guy, who...

-Are there any Intellectual Property restrictions after so many years (decades)? For the shape, I doubt it. Again, you cannot assign IP to a shape or widely accepted concept like a car...parts of the car, yes, a car, no. Change the outer mold line and you should be ok.

I live this stuff and we have always, and I recommend this, reached out to the OEM. You don't have to divulge a think, just see if they care. For instance, Raytheon builds a jamming missile, MALD, that I was asked by the Pentagon to do design excursions on. So we did...all data from the public domain (insane amount of design data on line for MALD and I don't know why).

After they folks liked what we did, we contacted Raytheon and I thought there would be a phalanx of lawyers parachuting into our small company to cease and desist.

They loved it and we are still working together. Communicate first.

Long post, just get a Guy or Gal, five hours time and you should be clear. Worth the money.