Tell them Frank sent ya and ask for a free sample newsletter and school info. As long as your car is in good running condition and can pass a required safety inspection at a designated shop you can run any car you want.
Most people are concern about running at the track with their bone stock cars.
They think their car need to be tricked out to do the school. It is actually better for you to learn in your stock car. You will be surprised by the ability of you car. In a good driver's hands, it will do things and turn lap times much better than you thought possible. One of the main goal is to have lot of fun, and take the car home.