Abstract
The most attractive theoretic fuel economy potential of Gasoline Direct Injection can only partially be utilised within the constraints of EU IV emission legislation. Instead of 20 25 % improvement expected some years ago, compared to best of class MPFI currently about 10% can be obtained. Investigating the potential not yet utilised, not only various influencing parameters can be identified, but also concrete measures for further improvements can be defined. Thus, assuming availability of low sulphur fuel, a fuel economy potential of about 15% even within EU IV constraints can be expected. However, the durability of the exhaust gas aftertreatment system still has to be proven.
The application of GDI Technology clearly favours the combination of other fuel efficient technologies like downsizing by turbocharging or variable effective compression ratio by in-take phase shifter. As GDI technology improves some deficiencies of these technologies we expect that the predicted potential (up to more than 25%) can also be utilised in real customers use.