Hi Ron! Ok...let me explain...there are two different types of events. One is a track event, which is just like the bikes...but more expensive
You are grouped according to your experience and skill level regardless of your car. Your whole group is out on the track at once, but there are passing rules, passing zones, instructors, etc to keep it safe.
The second type of event (which I think Soda is referring to) is called an autocross. That's when they take a big parking lot and set up a course with cones. You are classed according to your car, not driver ability. The cars are released one at a time to take one lap through the cones and your times are recorded. You'll get between 8 and 10 laps throughout the day and naturally the fastest timed lap wins the class.
You can do either of these events with any type of car as long as you have a passenger seat and two matching seatbelts. Modifications to the car are not necessary. There are all types of cars that participate in either of the events from Porsches, BMW's, Ferraris to Honda Civics, Evos, STI's Miatas, and yes even Buicks.
I do my track days with a group called PDA. They run at Pocono, Lime Rock, Watkins Glen, etc. Their website is
www.pdadrivingschool.com, if you wanna check it out. As for autocrosses, I'll run with either SCCA (NNJR chapter which runs at Englishtown) or Motorsports Northeast, which usually runs at the Meadowlands but just got two dates at the Somerset Patriots Ballpark (one is this Sunday 6/4). Their website is
www.motorsportsne.com. Also a friend Perry has a website
www.autox4u.com. He runs the SCCA NNJR events but his website includes links to all the clubs in the area.
Hope this helps! If you have any questions or need anything else, let me know.