Hacking a car "in real life"

As reported on Wired in March 2010:

More than 100 drivers in Austin, Texas found their cars disabled or the horns honking out of control, after an intruder ran amok in a web-based vehicle-immobilization system normally used to get the attention of consumers delinquent in their auto payments.

Other than that, not much, as Sophos says:

The dangers of cyber attacks on cars has all been theoretical so far: at this point, there’ve been no real-world attacks, as far as we know. Only security researchers have managed to send cars into the weeds.