Guess who is a huge fan of water injection, David Vizard
https://www.youtube.com/watch?v=jextyKc2UN4&t=85s
Its about 40 some minutes and worth the watch. In it he speaks about a idea for a gas mileage engine. I always wondered why they never tried a small 4 cylinder engine that has very high CR and uses water injection. But he takes it one step further. Instead of a cylinder every other stroke, it skips a normal cycle and uses heated steam to push the piston down. Which also cools so you can delete the radiator.
Heat= energy and the heat energy that is wasted could be used to push the car forward.
Most of the early research on water injection came from WWII. He mentions P-47s, Corsairs(the best IMO) and the P-51.
Water injection has come a long way.
Here is the company he recommends. A UK company.
https://aquamist-direct.com/aquamist-all/
This is the forum for that site which looks exactly like the defunct PZ site.
http://www.aquamist.co.uk/forum2/vbulletin/