Why can't a car function without gasoline?

Answer 1

Cars burn gasoline. Gasoline is pumped into the engine's intake, where it is mixed with air, called an air/fuel mixture. After it is mixed, a valve in the engines cylinder head opens and draws the air/fuel mixture into a cylinder. The valve closes and traps the mixture in the cylinder. In the cylinder is piston which moves up and compresses the air/fuel mixture. In the top of the cylinder, in the cylinder head is a spark plug, which ignites the compressed air/fuel mixture. The mixture explodes and forces the piston back down the cylinder. The piston is connected to a shaft, called the crank, which is connected to the car's transmission, which is connected to the car's drive wheels. When the piston is forced down by the exploding air/fuel mixture it forces the crank to turn, which turns the transmission, which turns the wheels. Without the gasoline, there would be nothing make the explosion which drives the car.

Look at the linked page for a more in depth explanation of how an engine works.