I'm a lawyer - but I do criminal law - so I'm not much help.
Unless of course in a fit of rage over your blown motor you assault your Porsche dealer and get arrested..
Seriously - I'd like to hear from some of the civil attorneys here on the forum. What I do as a criminal lawyer tends to be more focused on trial work - and not on civil litigation/discovery/motions. Those guys can speak to the strenths/weaknesses from a liability standpoint.
What I can comment on, as a trial lawyer, is that a case like this would be a tough sell to a jury. EVEN IF PORSCHE IS LEGALLY LIABLE (and I don't know that they are) - good luck getting a jury to give a rats a$$ about it.
Jurors don't just listen to a case, listen to the law, and then actually follow the law. They are supposed to - but guess what - they don't. Ever hear of a guy named OJ??? Jurors are not judges and lawyers. They are lay people, not necessarily the sharpest tool in the shed, and they are often times motivated more by emotions and lay person standards, than the actual law the judge reads to them. So even though you may have a case from a "legal" perspective, you still need to make Joe Six Pack care enough to find the other guy liable and pay you money.
A bunch of Porsche owners who are complaining that the engine was poorly designed because it broke when it was OFF warranty will not generate much sympathy.
The average joe - who will be your jurors - don't own Porsches. They think anyone who owns one is rich enough to fix anything that could go wrong with it, and they will figure if you bought a Porsche, you assumed that risk when you bought it.
Imagine Donald Trump trying to sue the manufacturer of his private jet because the engines took a dump after the warranty expired. Would you let "The Donald" collect from the maker of his Gulfstream? That's kind of how the guy in the Accord will view all the "rich" guys whining about their Porsches...
Like I said, I'm not a civil attorney - so I hope I'm wrong - I just think that if/when this case made it to a real courtroom with a real jury - no one would care - and that matters.