Jinndar

Hello, I am by no means a scientist, but more of a curious thinker. Today I saw a video news clip about the car they have developed to run on H2O. I knew they had developed a bus a while ago, but finally a smaller car. I believe the operation of the car is this, the water is split into Oxygen and Hydrogen, then the Hydrogen is then used to move the car. I assume the Oxygen is released into the air. Now my question is this. 1. Does water eventually become non existent? 2. And after the Hydrogen is combusted does that chemical change get fussed again with oxygen later down the road? Sorry for my ignorance with the questions and my ignorance with the science itself.