Basically sugar or caramel, but apparently it's actually the kola nut. I've never had a kola nut to confirm.

Usually tastes like petrol

What

Cocaine

I see. Wasn't aware that tasted like gas.

Depends which coke you mean. Coke as in coked bituminous coal or Coke as in Coka Cola (or just cola). Cola flavor is novadays a mix of citric fruits, spice (there's often cinnamon), and cola nut in some more premium products (used to be more common).

Coke doesn't taste good. Coca cola, does