With millisecond accuracy, DFI injects fuel at a pressure of up to 1740 psi directly into the combustion chamber by means of electromagnetically actuated injection valves.

The spray and cone angles have been optimized for torque, power output, fuel consumption and emissions by enabling a homogeneous distribution of the air/fuel mixture, and, therefore, effective combustion. With direct injection, the EMS SDI 3.1 engine control regulates injection timing individually for each cylinder as well as the injection rate for each cylinder bank. This optimizes the combustion process and fuel economy. A hot-film air mass meter takes care of the airflow, so that the combustion chambers contain exactly the right mixture at all times.

At up to 3,200 rpm, the engine operates with dual injection; at up to 2,500 rpm, it even works with triple injection. The required volume of fuel is distributed between two or three sequential injections, respectively – for faster heating of the catalytic converters after a cold start and for greater torque in the upper load range.

DFI improves the internal cooling of the combustion chamber by having the mixture prepared directly in the cylinder. This allows for a higher compression ratio (12.5:1) which helps to deliver more output along with enhanced engine efficiency. It has therefore been possible to reduce CO2 emissions by up to 15%, depending on the model.

Injection is regulated by the electronic engine management system. The exhaust gas cleaning system ensures that emissions remain well below even the strict limits of the EU5 emission standard, thus helping to protect the environment.