The M4 GTS was just a test bed. Now we get the real deal.
BMW came up with a laundry list of reasons as to why the M4 GTS was so much more special than the M4 in order to justify its $161,972 price tag. One such reason was the Bimmer's fancy water injection system that was supposed to use H2O to get more power out of its performance engine. Sadly for the GTS, that feature won't be special anymore thanks to Bosch. Autocar has just broken the news that the auto parts supplier has made the decision to make the technology widely available to other automakers.
As much as we'd appreciate the extra power unlocked by the system in our pedestrian sedans, Bosch claims that it isn't horsepower numbers that are being taken into account. It's the ever tighter fuel economy and emissions restrictions that are responsible. The system works by spraying a fine mist of distilled water into the intake prior to the combustion phase, which in turn cools the engine and prevents power and mileage-sapping knock. When stacked up, that simple water spritz packs a real punch. CO2 emissions go down by 4%, fuel economy goes up by 13%, and in the M4 GTS power is boosted by 5%. Bosch global product manager Fabiana Piazza told Autocar the system's effect can be felt on engines large and small.
However, the technology usually tends to work better with motors making more than 107 horsepower per liter. The system is nearly identical to the one present in the M4 GTS. In fact, BMW collaborated with Bosch on the unit and used the GTS as a sort of test bed. As we have seen it looks like the results are pretty spectacular. It would seem like water would dumb down the explosions and dull the exhaust note, but that's not the case at all. As with the M4 GTS, the tank of water will need to be refilled every 1,800 miles. It's worth mentioning that given the vapor state of the water, engine rust is not a concern. Look for the first applications in 2019 after Bosch finds out how to keep the water from freezing in colder regions.
To see how the system works for yourself, check out this video below.