View my fuel log 2016 Micra Active manual: 6.0 L/100 km ... 46.9 mpg (Imp) ... 16.6 km/L ... 39.0 mpg (US) ...
Probably only applicable to high output engines though - where compression is so high (eg turbo/supercharger) that the water in the intake charge helps prevent detonation. Otherwise, the computer would have to retard timing (which hurts power & fuel economy).
BMW was the first customer to use Bosch’s system, adding it to the high performance version of its M4. By reducing engine temperatures and knock, water injection helped push the vehicle’s output from 425 horsepower to 493. Torque saw a similar bump.
View my fuel log 2015 Micra S manual: 5.0 L/100 km ... 56.5 mpg (Imp) ... 20.0 km/L ... 47.0 mpg (US) ...