Hi sologap,
Yes, it is possible with modifications to an OBD II (with ELM 327 Bluetooth/wireless -
https://scantool.net) that would also need access to the blockchain and can sign transactions that could be used with an iPhone/Android based phone. We could work with the car manufacturers/rental companies and have access to the "proprietary" codes to unlock door locks (
http://www.obdsol.com/solutions/chips/stn1170/) etc... That would be the only barrier to entry besides adding a chipset to an OBD II board...
Imagine if the car manufacturer created an asset on the blockchain and then associated the IoT device to the asset?

Regards,
ASIC-8Tile
can rent a car companies use this ? maybe they add a sensor in the cars to show location on a map then renter can pay with XTC and just go to car location and open door ?
