Everyone is freaking out...
But I have to ask, just how relevant is some of this 'super secret' information that may or may not be collected? I can see how throttle position and vehicle speed and RPMs could be used to determine (somewhat) if a person is racing their car, or (indirectly) possibly breaking traffic laws when combined with GPS, if analyzed to death, and if the data could be matched to a user ID.
But what mayhem is Google or anyone going to do with data such as oil temperature or pressure? Determine that someone doesn't like to warm up their car before they get on the highway? Market oil changes? Determine that you're a bad person because you have premature engine wear or aren't driving "green"? How in creation is any of it going to benefit a "automotive competitor" that has dimwitted self-driving cars that putz around town slowly like ants carrying bread crumbs on a sidewalk?
I realize that having an open avenue for data to be exchanged with a car's systems by an Internet-connected device is a very bad idea, and could lead to all kinds of unpleasant exploits. But that doesn't seem to be the point of this decision. Though while we're on the subject, what data is marketing king Apple secretly gobbling with even less openness? I really just suspect that Porsche 'drank the Kool-aid" and caved because iStuff is perceived as being more hip among the pretentious set, and most people that buy Porsches are likely to have an iPhone. Not because they respect the performance of Porsche or its racing heritage, or that iPhones are better in any meaningful way functionally, but "ooh, shiny!"
Realistically, is either company less scummy with your demographic data? What are cars that boast built-in 4G connectivity without using a phone blasting back to home base about your driving habits, location, and other data? If you want to go in that direction, GM's integrated "OnStar" system, which preceded all other systems of this type, is probably the spymaster of the bunch.