Mercedes CGI System Saves Fuel

A new 3.5-liter V-6 from Mercedes-Benz is the world's first direct injection gasoline engine with piezoelectric injectors and spray-guided combustion. Known as Stratified-Charged Gasoline Injection (CGI), the system helps the engine outperform the fuel economy of its conventionally-injected counterpart by up to 15 percent. In the CLS 350, the first application of the new engine, this translates into fuel economy ranging from 25.3 to 25.8 mpg on the European cycle. The engine will replace the current V-6 in the CLS 350 in Western Europe first, but will likely spread throughout the Mercedes lineup and, hopefully, throughout the world.
 
The most important component in this new direct-injection system is the fast-acting, high-precision piezoelectric injector. The microsecond response time of the injector allows for multiple injections per combustion stroke, allowing the engine to run in its highly efficient lean-burn operating mode over a wider load range. In addition to higher efficiency, the engine is cleaner too. Engine-out hydrocarbon emissions in the warm-up phase are almost halved and, since the injection and combustion processes can be actively controlled, it is possible to raise temperatures in the exhaust manifold and thus speed catalytic converter warm-up.