In an internal combustion engine expanding gases create high pressure within the combustion chamber, and since the chamber is sealed by the cylinder walls and the piston, the pressure forces the piston to move. The piston moves downward due to the force exerted by the expanding gases, which pushes against the piston head.

Two ways water cars are communicated to work is trying to maximize phase transition from water to steam and adding hydrogen. When maximizing combustion, adding water will only really get in the way and easily diminish performance like so many products do that interfere with the combustion cycle.

Sequestration of exhaust using a simple water filter is probably an easy solution for more environmentally friendly vehicles.

What is really required is improved battery technology for the reason that everything we use in our daily life relies on battery technology and if automotives use batteries then batteries are more likely to improve over the years. The internal combustion engine has not undergone any significant advance in almost 100 years.

To be resistant to experimentation is holding on too tight, after all modern life with all its luxuries had to be invented some time in the past to be beneficial, acting as if you at the end state is a low grade mind.