Was it Toyota or someone else? How much would it cost GM if they wanted to use the Toyota design?

I have spent at least some time on questions having to do with the historical development of technologies and the question "who invented X...?" is normally not something than can be answered. The reason is that you usually find that no ONE (person or company) invented a thing and you also find that the definition or concept of "the thing" floats a lot. It can get stabilized at some point, and if it does then people can reconstruct history and sometimes attach something to an inventor. It still amazes me that our culture contains the myth that Thomas Edison "invented" the lightbulb. (He didn't. First, there wasn't a "moment" when the lightbulb suddenly existed when it hadn't before. Second, for the specific design elements that Edison patented he was a year behind a British inventor named Joseph Swan to whom he lost a patent dispute. Networks of people operating over time "invent" - specific actors don't).

So when it comes to what it would take for GM to use a Toyota design I'm pretty sure you'd be talking about a collection of specific patents that they would be licensed to use. Does the GM/Toyota joint venture (NUMMI) still exist? It seems to me that if anything were done it would happen in that context and Toyota and GM could "trade" services.

That info sort of warms my heart - though I don't know anything of Severinsky. I say it warms my heart just b/c large corporates have a huge edge in patent disputes - tons of legal expertise on retainer and at the ready. One of the things that contributed to the decline of independent inventors soon after the turn of the century (not that they don't still exist here and there) was the rise of corporate R&D - and their much better funded legal departments.

I wouldn't be surprised though if Toyota wasn't clearly aware of the infringement (never know). That's just b/c most people working in a tech area are all reading the same journals & going to the same conferences etc. (Edison's library of sci/tech journals & patent reports was extensive). That's why I say networks are the inventors, rather than people. An actual individual tends to get credit, but this happens for weird and somewhat unpredictable reasons.

Anyway, I say good for Severinsky, though obviously Toyota found the end around.

Toyota could easily have known that a patent existed. They employ people to sift through patents to make sure they know if anyone has prior art claims. In this case, they either must have known or messed up very badly. My guess is that they know full well what Severinsky's patents said, and tried to get by with it anyway. Toyota is a sophisticated, powerful organization that would not be where they are today by routinely making unprofessional blunders, if that's what it was (I think not). You may recall a movie about the inventor of the intermittent windshield wiper, and how Ford ignored his patents, though they were fully aware of them. He got paid, too.

Mr. Sanders is correct about the story about Toyota and the infringement. I remember reading a magazine article on that some years back.
You wonder just how many times little guys get overwhelmed by a large business, a building full of lawyers, and give in rather than fight.

Some decades back a gentleman sued Sears over the Craftsman ratchet push-button socket release. Apparently this was his idea and was stolen by Sears who went on to sell countless millions of these ratchets; and still do.
The court awarded the designer something like 25 million dollars based on total ratchet sales but I never heard what the end result was. Sometimes the Appeals court will overturn large awards.