Did you not go the official MB website.
I am there tomorrow afternoon.
From all the invite track type events they set up small track events to feel the handling.
If they think you are not driving safely or that you are going beyond your own skills they will warn you before asking you to leave.
That said as long as you aer extra nice to people you can get to have some fun, That is what i did and got to get a slight drift in a mini on a small course of a reducing radius turn they had.
Well i went today and there was like 5 people so i got to have some fun.
the B class actually handles the best with its 2.0L turbo.
Not a bad track set up just basically a bunch or tight turns nothing in the way of a straighaway.
They also had some nice burgers and pop for free which i enjoyed.