Just one thing to clarify... the free "M Driving Experience" that they give with M5s and M6s (and a few lucky M3s) is VERY different than the paid M Driving School.
While the M Driving Experience was still a lot of fun, there was very little instruction. You spend about 50% of the time experiencing the safety features of the cars (DSC and ABS), then you get to spend the other 50% doing little track drills.
They don't actually teach you how to drive better... just let you drive harder and faster than you would on the street under similar conditions.
The paid school is worth every penny... but the free version may not be worth it if you have to pay a lot to travel to SC. Just my opinion.
2008 e92 M3 - 6MT - Space Gray + Fox Red
2009 e90 335i - Loaded
2006 X3 - Lame (sits in the driveway)