Iveco and Shell have collaborated in a test programme on diesel emissions, which has investigated the effect of diesel fuel properties, in conjunction with the effect of fuel injection timing, on the regulated emissions from an advanced heavy-duty diesel engine. This study has contributed complementary information to that generated in the European Programme on Emissions, Fuels and Engine technology (EPEFE). Tests were performed over the R49 (13-mode) European cycle. The experimental programme covered a range of fuel properties, similar to those investigated by EPEFE (density, cetane number, polyaromatics and back-end distillation (T90)), but also included total aromatics. Fuel sulphur content, being relatively well understood with respect to particulate emissions, and in the absence of an oxidation catalyst, was not investigated. Care was taken in the preparation of the fuels to maximise the decorrelation of the selected properties.The selected engine was an Iveco 9.5 litre 6 cylinder 8460.41 prototype Euro. 2 truck engine. This was operated under both the standard injection timing setting, and under adjusted timing conditions for fixed NOx emissions. This timing compensation allowed an insight into how potential benefits in lower NOx emissions can be traded against the normal fuel consumption (BSFC) penalty from timing retard.The emissions analysis concentrated on particulates and NOx which are two of the key emissions identified in the air quality modelling of the European Auto / Oil programme. Results are compared with those published from EPEFE and other recent work.