In my opinion The ZR-1 record car was still a production car, even with
all that tuning, because you can do these modifications to your ZR-1
without any problems. It is a car like yours, a car you can buy.
A car like the VW Nardo is a prototype, a purpose built car for what ever!
It's not so easy to get one and have it parked in your garage !!
Best greetings from Switzerland,
Franz