Offer a button to turn off the car from app, will make stealing of the car less likely. When the car moves without the owners cellphone closely the car sends an sms and the owner can shut it down remotely. If the car is moving faster than a certain speed a countdown could be started.
Moderator: There are some legal/safety concerns that may prevent this option. For example, if someone hacked your account or even partner you gave access to your account, they could stop you on the freeway and cause a major accident. Of course if the thief steals your phone at the same time, this option becomes moot. There are likely ways to overcome these issues, so it’s a viable option.