Road Vehicle transport is just one application of crude oil. Ships and aviation sector also use fractions of crude oil. Crude oil is also used to make other valuable chemicals like aromatics, cyclic alkanes, kerosene, asphalt, hydrocarbon solvents, LPG cylinders for cooking food, lubricants,wax,tar, coke olefins like ethylene and propylene which are further used to make oxides and polymers, etc
46% from a barrel of crude oil in USA is used as gasoline in vehicles. Rest is used for other applications.
The population and so demand for crude oil is also too much for applications other than gasoline in the world.