Car fuel is burnt in the engine. Spark plugs ignite the fuel and the explosion (the hum of a car engine is actually loads and loads of really tiny explosions) pushes a piston up which drives the axle of the car and the wheels round.
This explosion produces different chemicals like carbon dioxide, nitrogen oxide and can make nasty things like carbon monoxide depending on how good the engine is.
Car fuel, like any fuel, need oxygen to burn, so your engine has inputs of oxygen, and of fuel. Old cars had a ‘choke’ where you had to manually control how much petrol vs oxygen you put in, but modern cars do it automatically. Spark plugs ignite tiny pools of fuel, which explodes and pushes a piston – I think cars usually have about 4 pistons – that then is turned into rotational movement through some funky levers.
Then more petrol and oxygen is put into the pistons and the whole thing is repeated 150 times a minute!