I'm am not at all knowledgeable about class actions suits, but to me this seems rather silly. This is the first that I have heard of this "problem". If it was worthy of a class action lawsuit, wouldn't it be more widely know, at least in BMW forums? I don't have the NAV system, and I have noticed that compared to other FM car radios I have, the HK definitely has a weak front end (the part of the radio that receives and amplifies the RF signal). But since BMW doesn't advertise receiver sensitivity specs, what standard can they be held liable to?
I'm not bashing class action suits, they have their place, but class action suits of this level make money for the attorneys and no one else.
As far as the SLIPTronic issue, BMW is taking full responsibilty for the problem. What is the purpose of even suggesting a class action suit at this point? [???1]