Horses will make a comeback on a massive scale. They'll eat hay and grain and their own gas -- wait a minute they woud cause air pollution -- there goes the ozone layer!
We can utilize the used grease from fast food places to run our vehicles -- wait a minute, we'd all smell that french fry exhaust and be hungry for more junk food.
We could run our cars with batteries like the pretentious snot box the Prius -- wait a minute, it ruins the environment digging for the minerals used to run those batteries and then they become a deadly land fill problem.
We can run our vehicles on corn/ethanol -- wait a minute, if we divert corn for cars/trucks that means we can't feed the world's starving people. Cars or people?
We could walk or ride a bike to and from work like the Chinese -- wait a minute, the rich will have access to fuel t run their limos and run the pedestrians/bycycalist over.
No matter what we choose the choice will be fraught with problems. I have faith that everything humans need to survive can be found on this planet. There are all sorts of options besides oil. We can recycle all that old plastic to make new products. We can become more frugal with all our resouces. We did so in WWI & WWII, we can do it again.
Don't worry, be happy.