We must wait for the global regulation of bitcoin and altcoin to be used as a valid currency for various payment methods. If the regulation has been made and all countries in the world agree and support the regulation then you will easily be able to buy a car using bitcoin or altcoin because car companies will accept the bitcoin payment method because it refers to the global regulation of currency digital like bitcoin. But, right now we just have to wait for the development of bitcoin alone because the blockchain technology that is in bitcoin is really able to help the world economy in any form.