The privacy concern is valid. It won't be long before all new cars are sending data from the sensors to third parties, and it would be unthinkable for the manufacturers to ask for your consent before collecting that data since they'll make money off of it.
The article mentions concerns with insurance companies. One I worked for tried to get customers to agree to having their rates adjusted based on data from their cars. It was mostly to do with how many miles the customer drove, but I think there was also an element that looked at speed coupled with GPS data to determine if they habitually exceeded the speed limit. There was a lot of pushback from customers and privacy advocates at the time and it didn't really go anywhere at the time (2007-08 iirc) but since that time I recall hearing of another company doing just that with some volunteers.
Now imagine the insurer has access to everything on the CAN bus. Your rates could go up based on taking curves too fast, braking too hard too often, or following too close.
The law enforcement angle is disturbing too.
Then there's the nightmare of the advertising people getting hold of it, complete with GPS data. God knows what they'd do with it exactly, but whatever it is, it will be sleazy and annoying by definition.
Time to include this on the list of things to oppose for privacy's sake.