There are many tasks that we do that do not require burning petroleum. Often when I need a small item at the local hardware store, I ride my bicycle to the store rather than driving in my car and using gasoline. I get some exercise, save a some money on gasoline, and avoid polluting the air with vehicle exhaust gases.
Our crude oil reserves are a finite resource that we will need in the future even if the oil is not used for motor fuel. Oil is needed to make products that we depend on, such as plastics and other organic chemicals.