"the way I read its is that no, BMW is NOT legally required to release it as it is in a proprietary piece of HW, and releasing the code could thus cause harm to their business."
When in the hell did the "Release sources, unless it would do harm to your business" clause get added to the GPL?
"no one can prove that they were HARMED or had a loss of income or even IP"
Sure they can. It's their IP, and if BMW wanted to use it, they had to follow the license, or negotiate for a private license. They did neither, which very much would constitute harm.
"is essentially 'free' in that no money or barter items were exchanged."
The barter is that you would "pay it forward". BMW has not upheld their side of the bargain.
"They MAY have a copyright claim at best"
They're the ones who wrote the software; they're the ones who decide how it gets licensed. If that license is broken, then their copyright was violated.
"Is there a precedent to enforce GNU licensing outside of copyright infringement?"
When in the hell did the "Release sources, unless it would do harm to your business" clause get added to the GPL?
"no one can prove that they were HARMED or had a loss of income or even IP"
Sure they can. It's their IP, and if BMW wanted to use it, they had to follow the license, or negotiate for a private license. They did neither, which very much would constitute harm.
"is essentially 'free' in that no money or barter items were exchanged."
The barter is that you would "pay it forward". BMW has not upheld their side of the bargain.
"They MAY have a copyright claim at best"
They're the ones who wrote the software; they're the ones who decide how it gets licensed. If that license is broken, then their copyright was violated.
"Is there a precedent to enforce GNU licensing outside of copyright infringement?"
Why would there need to be?