The kit is a tube frame, very rigid, with body panels (carbon fiber available, but costs extra). You build the car with the motor and running gear of a C5 corvette. Because the car is mid-engine, rear wheel drive, you need a different transmison.
I love my Z and plan to keep it and continue modding it for solo racing and driving around the country. I would never put my Z in danger of a hit from another race car though.
With a Mulsanne, I would tune it for the track only and I wouldn't be emotionally invested in it. And you can build it for $40k or less. Now that's a car worth dreaming about. I wouldn't even consider a Ferrari (although my g.f. says we should enroll in that "rotating exotic car rental" program).