What???? I think you read too many conspiracy sites and I guess I'm just an idiot.
No, I actually read about this stuff
Car companies (I think it was GM specifically) admitted to viewing it's driver data as a product and having a desire to monetize it with insurance companies. And if one of them is doing it, they're all doing it.
Car companies have also historically fought very hard to keep their control systems completely closed, sometimes even to their own developers. They assume they're secure just because they're cars. And this gives you issues like the recent car hacks that take over everything, including acceleration. These issues have been written up in car, engineering, and development mags for years. None of this is new.
I've worked in IT, and I don't mean as a Windows monkey. I have been asked to run metrics on users. Taking information, accessing geolocation databases, correlating data and creating graphs and whatnot. It is not hard. And if I have been asked to do it in the small companies I've worked for, I guarantee you that it's happening in much larger companies. They don't need OBD2 data to understand your private comings and goings. Unless you live in the woods off the grid without a cell phone, you have little to no privacy. It's just the way it is.
As for conspiracy? I don't believe the government at large has the organizational prowess to actually invade our privacy as much as people think they do. They still mandate companies collect it, though, and that applies to everyone equally regardless of your phone or car choice. Advertisers have the desire to work with this data, and they don't need your OBD2 info to accomplish their goals. Unless their goal is to help find you a mechanic when your engine drops below an expected efficiency threshold.