And while flying and water-powered cars remain exclusive to science fiction, hydrogen vehicle engines could be the future.

So, while water-powered engines do exist and have practical applications in space exploration, we're unlikely to see them rolling around in ground-level cars any time soon. Want the latest in tech ...

As intriguing as all of this sounds, it bears mentioning that water-powered cars have repeatedly failed in their missions (see here) of offering nearly free fuel for all.

Some inventors talk about exotic ideas such as water-powered cars and magnetic engines. And then there's the diamond battery, which is said to run for thousands of years without needing a charge ...