I came across interesting articles on what could be the fuels for our cars and planes in the future. This is for the moment just research, but there is no doubt that with peak oil approaching, alternatives are being sought.
Even if most if not all cars nowadays run on gas, they could well soon use urine (via hydrogen engines) or carbon dioxide in the future. Similarly, planes could be powered by algae.
Even if these new energy sources aren’t due to be used any time soon, it is good to know that low carbon and renewable alternatives could be used for all our transportation needs one day.