Actually, it's true that most of Reaction Research's kits are for Datsun Zs, but they designed and built this kit for the BMW Z3.
This is what it says on the official website:
"ZGT is a coach-built composite body for the 1996-2002 BMW E36/7 "Z3" platform. The Z3 was produced in large numbers, thus is readily available as an inexpensive donor platform."
This from a knowledgeable website:
"While John Washington of Reaction Research has been using Datsun Z-cars as donors for many years, his latest project employs a whole new type of Z-car, the BMW Z3."