"The aim of the fellowship is ‘to achieve minimum cycle-to-cycle variations for a smooth cold start and robust idle speed operation and reduced particulate matter emissions during engine transients’. Latest engine design trend is towards lower compression ratio and higher turbocharger boost in order to achieve higher specific power and lower pollutant emissions, which raises the concern over cold-start operation. This problem will be much more severe if the diesel fuel contains higher percentage of biodiesel as per the proposed European fuel policy. This is one of the key research areas for the automakers and oil companies. However, optimization of cold start process is a trial-and-error procedure and with poor repeatability in engine test benches.There is little data for transient measurement of emissions during the cold start and in fact, very little research on the engine transient regulatory test procedure was reported. Moreover, in the present scenario, exhaust particle number and size distribution is the prime importance in Euro 6 (or beyond) emission regulations. There is no reference data available for the particle emissions of biodiesel engines in terms of exhaust particle number and size distribution during the start phase and transient operation.Hardware-in-loop simulation model that can simulate engine transient behaviour accurately is proposed for the cold start of diesel engines in the cold transient test facilities, especially with biodiesel. It is also proposed to assess the cold start performance of diesel engines and analysis gaseous emissions and particle number & size distribution using different biodiesel blends at start phase and transient condition. With the new legislation on particulate matter coming to effect very soon, these data will be critical in the implementation of particle number and size limit in the future European emission norms."