You're totally off. All those things you said _can_ go on the blockchain including the private key that they could use to start the car. Of course they can sell it for parts...if the parts didn't have private key protection too...
Someone has to do the data entry into the blockchain. You end up having to trust this person, which completely negates the purpose of the blockchain: trustlessness.
For supply chain issues the Oracle problem is very apparent. How does your smart contract know if the shipment has actually reached its destination?
