It also keeps the combustion chamber spotless (steam cleaned) and as the water is heated during combustion, it expands into steam salvaging some of the usually wasted heat energy, I'm not sure how much the steam would contribute to power but I think it's probably not insignificant.

I've often wondered why this is common practise in modern vehicles. I think it's probably something to do with the perception many people have (even mechanics) that ANY water will destroy an engine.

rally racers have been doing this for years. The cooling mist sprayed into the combustion chamber cools down temps, and allows the turbo to cram in more air, thus making more power. Its not a stretch to see how this will improve fuel economy. I run an aquamist system of my own in a vehicle, but its not to save on gas. However, its been known in the racing communit for quite awhile, that mixing a small bit of ethanol in with your water does increase mpgs.

So what happens during that part of the year when one doesn't run the airconditioning? Which, in Germany for instance, is about nine out of twelve months? No water, no water injection?

Been used in trucks for years.

It was invented in Poland by Jan Gulak many years ago not by BMW. Try to find on youtube "auto na wodę".

Old invention used in WW2 just a new usage.

My old Austin Healy Sprite always ran better on Cool moist foggy nights. Anybody that has owned an old British cars knows the benefits of water as a combustion component.

Everyone should notice an increase in cool humid evenings where the maximum dew point is being reached... lost of extra zip

If it's good enough for modern jet engines and older WW2 piston engined fighters then it's certainly good enough for todays cars.Really,this is a technology that should have been in automotive use long before now...

My grandfather had a water injection system on his car in the 1950s. There was a gallon jug of water mounted inside the engine compartment with a line to one of the vacuum lines on the carburetor. He claimed it increased his gas mileage.