ECU hack sound like the Jeep one a few years ago
Manipulating the infotaiment system to obtain access to the ECU: https://www.theregister.co.uk/2015/07/21/jeep_patch/
If this could have been controlled over the cellular network (3G is mentioned in the article) then it could have been a completely remote attack. Send the mark a crafted email to follow a malicious link, they click on it whilst in the car and it then exploits the infotainment system to talk to the ECU and provide a connection back to the attacker?