Mercedes-Benz CLS350 CGI
The 2007 Mercedes-Benz CLS350 CGI is the world's first petrol engine featuring piezoelectric direct injection and spray-guided combustion. The 215 kW/ 288 hp six-cylinder engine of the CLS350 CGI consumes about ten percent less fuel than a comparable V6 petrol engine with port injection.
The world's first direct petrol injection system with spray-guided combustion points the way ahead for passenger car petrol engines. The engine's innovative injection procedure makes for much better fuel and thermodynamic efficiency than the wall-guided combustion process previously employed with direct injection. With a fuel consumption of 9.1-9.3 litres per 100 kilometres in the European driving cycle, the six-cylinder Coupé has a range of approximately 70 kilometres on one tankful (80 litres).
The main advantage of the CGI engine (CGI = Stratified-Charged Gasoline Injection) lies in the stratified operating mode from which it takes its name. In this mode the engine is run with high excess air and thus excellent fuel efficiency. Now, thanks to multiple injection, it is for the first time possible to extend this lean-burn operating mode to higher rpm and load ranges too. During each power stroke, a series of injections takes place, spaced just fractions of a second apart. This has the effect of significantly improving mixture formation, combustion and fuel consumption.
Among the most important components of this innovative direct petrol injection system are the fast-acting piezoelectric injectors. They have nozzles which open outwards to create an annular gap just a few microns wide. This gap shapes the fuel jet and produces a uniform, hollow-cone-shaped spray pattern. The microsecond response times of the piezoelectric injectors provide the basis for delivering multiple injections per power stroke, and thus for lean-burn operation. By allowing flexible and efficient control of the combustion process they play a key part in ensuring the engine's outstanding fuel efficiency.
Low fuel consumption and excellent power delivery are not at odds with each other on the second-generation Mercedes-Benz direct petrol injection model. On the contrary, the engine delivers 15 kW/20 hp more power than the conventional-injection V6 and four percent more torque. Thus the CGI engine combines its excellent fuel economy with a level of effortless driving enjoyment that is unprecedented in the six-cylinder segment. This allows the new CLS350 CGI to accelerate from zero to 100 km/h in just 6.7 seconds on its way to a top speed of 250 km/h (electronically limited).
Source: Mercedes-Benz press