Would the corrosion problem be any worse than it is now ?
He is using rain water because it is delivered cheap and in SO Cal we don't have the contaminants like acid rain in other areas.
As soon as the exact science has been established, the project can move to a more practical application and allow water from more convenient supplies.
Expect to see a Sorta Diesel Rabbit not stopping at a service station near you.
As for class, it remains a Spark Ignition, NA Gas motor with water injection that is already allowed. But instead of curing a detonation problem it can make coffee.
