+1 on the Skip Barber Advanced Car Control. I took this class earlier this year at Laguna Seca and it was very helpful. I had previously taken the 3-day and 2-day and while those class really breakdown the basic and advanced techniques of road racing, the Advanced Car Control class really focused on just controlling the car at the limit. It's only one day but you are exhausted before the class is over. You really get to beat on the cars all day while you are learning to slide, skid and drift on both wet and dry surfaces. The instructors are always very good and I spend the day with Rene Villeneuve(ALMS), Mike Miller(Grand-Am) and Jeff Rodriguez. They gave me solid feedback and lots of encouragement.
My only complaint was the MX5s are setup for the track and they are very difficult to control vs the RX8s. Believe me if you can drift the MX5 with the Penske shock setup they run at Laguna, exploring the limit in your M3 will be cake.
Favorite Quote on Supercars: "They are designed to melt ice caps, kill the poor, poison the water table, destroy the ozone layer, decimate indigenous wildlife, recapture the Falkland islands, and turn the entire third world into a huge uninhabitable desert... but only after they nicked all the oil." Jeremy Clarkson from Top Gear 05x02 @ 48:55.