If the Penske GM has retained a lawyer, then he is expecting you to file a lawsuit against him and/or Penske. Granted if you do this, you could hurt their pocketbooks for a few hundred thousand dollars (depending on trial by jury or judge, and their estimate of Penske's fucktardedness to dollar ratio). But Penske is so large, I doubt it'll make a huge impact on their bottom line since every large corporation has a slush fund for lawsuits.
Instead, getting this story on every social media website, blog, major media outlets would really hurt them. If jalopnik/auto blog/etc publishes this story, Penske would really start feeling the pain. (Here is a short link you can give everyone or write on your portable billboard in front of their dealership:
http://goo.gl/z1X71) Right now, its your word against theirs, with BMWNA in the middle and the rest of us (who do not live near this dealership) saying we'll never buy from them.
You are doing a great thing here by fighting this the way you are, in a calm and respective manner, so that Penske knows they can't continue to be irresponsible and operate an unethical business. Hopefully BMWNA will come down on them hard, but as we both know, BMW only makes money from each dealership it has.
As I mentioned with our PMs, call me anytime.