When I read about it (Cliff notes version), it read as if the owners of the 2000 Indy's were invited to bring their cars to Indy to take a lap. What I read seemed to imply that you drove your own car.
Your Indy was apparently sitting at a dealership, for some reason, so may be different. For a dealership, this could only be a good idea. A great sales and marketing tactic.
I wouldn't let some random celebrity drive my Fiero. It'd have to be a car person, before I'd even consider it. Then someone I respected, like Tim Allen or Jay Leno. The last thing I'd want is some snowflake driving my Fiero (and probably wrecking it).
Besides, I'd rather drive my own car around Indy--I just wouldn't talk to the press.