The optimisation of the operating parameters optimisation for the IVECO small, high speed, turbocharged, DI Diesel engine for reaching Euro 3 emission levels, has been performed using statistical methods.The engine is equipped with a Common Rail injection system and some market versions are also equipped with a variable geometry turbocharger (VGT) as well as/or electronically controlled exhaust gas recirculation (EGR), hence, there are numerous operating parameters to be taken into account during mapping. The injection systems flexibility is very high. It allows independent injection pressures and timings as well as multiple injection throughout the entire engine map. Variable geometry turbochargers (VGT) enable the control of the optimal boost pressure. Finally consideration of exhaust gas recirculation (EGR) provides one more independent parameter to deal with.The optimisation procedure is very complex and IVECOs aim was to use more sophisticated, less time consuming and more precise ways for optimisation than the traditional R&D techniques, which are based on the so-called “one factor variation at a time” approach.The use of statistical methods for optimising the operating parameters throughout the entire engine map is proposed and demonstrated in this paper. Targets are the Euro 3 emission limits with minimum fuel consumption as well as minimum noise emission.