In the next few years, BMW aims to launch a series production car with the direct water injection system that the Munich engineers have been developing. The first mention of the water injection technology appeared earlier this year when the BMW briefly showcased a BMW M4 MotoGP Safety Car with the new system designed to increase the performance and reduce the consumption of combustion engines.

Next in line to receive the water injection system is the upcoming M4 GTS, but before the almighty sports car is unveiled, BMW has let us test the innovative technology in a prototype 1 Series Hatchback with the B38 three-cylinder engine.


The mad scientists at BMW have been working diligently on the new Direct Water Injection system which will essentially keep engines cooler, therefore increasing efficiency and power.

But as we mentioned before, Direct Water Injection isn’t entirely new to BMW, as it was used on the M4 MotoGP safety car. Basically what the system does, is spray highly pressurized water into the combustion chamber at the right time. This cools down the combustion chamber, reducing combustion temperature as well as engine knock. This is especially effective on turbocharged engines, as the high boost pressure creates higher combustion temperatures, creating knock and robbing the engine of potential performance and efficiency. Water Injection can increase efficiency by 3-8 percent in every day driving.


It is possible to lower consumption through the implementation of a higher compressions which would normally lead to uncontrolled combustion and, consequently, an engine knock. With the B38 unit, the compression could be increased to 11.0 thanks to the water injection of 9.5, with no negative on comfort and smoothness. The higher compression ratio in turn leads to more power, which is why about 218 hp can be generated by this 1.5 liter engine prototype.



It’s an interesting idea, using water to increase combustion efficiency, as water is normally used to extinguish fire, not aid it. But the clever folks at BMW have figured out a way to make it work. Water is stored in a 5 liter reservoir, which is then sent through a filter and then into the high-pressure fuel pump, where it mixes with the fuel. A sensor monitors engine speed and temperature to determine the correct amount of water for current engine conditions. At high speed and rpm, the fuel can be mixed with up to 30 percent water. This mixture is then sprayed directly into the combustion chamber at the exact correct moment. This allows for the chamber to be cooled dramatically before the next combustion cycle.


If you’re thinking that this is just another fluid for owners to maintain, think again. BMW claims that owners should very rarely, if ever, need to check or maintain the level of water for the Water Injection system. Also, in the hotter months, when air conditioning is often used, the system will borrow the condensation that normally drips onto the pavement from the A/C and feed it into the reservoir. So in the summer, the water reservoir will always stay full. Conversly, during the winter months, Water Injection is far less necessary, as the colder air and intercooler keep the combustion chambers cold enough, so the Water Injection system will be used seldom, reducing the need to maintain it. BMW claims that 5 liters should last about a year without heavy A/C use.


During those winter months, you might worry about the water freezing, but BMW has that covered as well. As the engine turns off, the high-pressure pump back flushes the water out of the system into the reservoir, to avoid the water freezing inside. The water may still freeze inside of the reservoir, but as the car starts it thaws the reservoir before the engine will get hot enough to need it, as cold engines are far less likely to knock.

Another added benefit of Direct Water Injection is power. Due to lower combustion chamber temperatures, engines will create more horsepower while using the same amount of boost. It also allows BMW to lower the boost and keep the same horsepower ratings, therefore increasing efficiency even further. But the real exciting prospect is what this can do to cars like the BMW M4, who will now be able to get even more boost, rev higher and run longer without the worry of overheating or damaging the engine.


A BMW engineer joined us for a lap around the Miramas private track where we tested the Direct Water Injection system under different loads and speeds; from 80 km/h (normal driving) to 130 km/h (highway speeds) and 180 km/h (race track or Autobahn driving). At the end of our run, the iPad installed in our prototype car showed an average fuel consumption benefit of 4.1 liter per 100 km (57.3 mpg) or 20.9 percent. In other run, the average fuel consumption was 2.82 l/100 km (112 mpg) or 18.4 percent.

The water consumption ranged from 0.09 to 0.11 liters, while the water accumulation per hour was projected at 1.7 to 1.9 liters.


BMW has used the substance that is most often used to extinguish fire to create better combustion. It’s so strange that it’s beautiful. This kind of technology and forward thinking is the stuff that keeps BMW at the top of the game year in and year out. Hopefully this technology will make it to road cars in the new future. Water Injection has been around on racecars for many years now, but no road car has ever seen it. So let’s hope that BMW can be the first to put a Direct Water Injection car on our streets.