He won the F3000 series before going to CART (and winning the Indy 500)... so he has come up the openweel ranks via the US.
Didn't Zanardi do it also (CART to F1), and Sebastien Bourdais?
The original point was IRL to F1. CART to F1 is slightly different, as I have said CART was run slightly differently to IRL and favoured more road/street courses than ovals.
In the end, IRL is not a feeder to F1, it doesn't offer a high-enough standard of competition and doesn't appear to give the right kind of experience. Its also not where the F1-talent scouts generally look as it tends to be the place where relatively unsuccessful open wheel drivers go when they reach the top of the European ladder but can't get an F1 seat.
The fact that CART drivers have even struggled in F1 really puts teams off though, there just isn't the known quantities that series like GP2, FR3.5, F3, etc have.
To put it back to the original, original point - I don't think Tony will have an issue handling the F1 car. It won't be done at flat out speeds and he isn't rubbish. NASCAR drivers aren't bad drivers. His IRL experience will obviously help but even a NASCAR driver with no previous open-wheel experience wouldn't bin an F1 car on what is effectively a publicity stunt.
There are far worse drivers who have been given real F1 tests who haven't binned the car.
I'd also say that reading into the times he sets doesn't really tell you much either - as with any racing car (but particularly an F1 car) its relatively easy to get within a few seconds of the ultimate speed, its the tenths of a second difference that are the hardest to find. People talk up Jeff Gordon's run but while it wasn't too shabby, its not really impressive to be within seconds.
The top drivers from any series put in any other car (e.g. Loeb in the Red Bull 2008, Raikkonen in NASCAR, Montoya in NASCAR, Senna in a rally car, etc etc) will always be within seconds of the top drivers for that other car. Its finding the last tenths of a second to secure victory that are the hardest and what sets apart the top drivers in each particular type of racing.