The impact of fuel composition (ethanol and aromatic content) and injector design on particulate number generation was studied in a 1.0L displacement direct injection spark ignition engine. Two types of engine tests that mimic real-life vehicle operation were carried out using a matrix of eight fuels and two injectors. It was found that the DISI injector design had the biggest impact on the extent of particulate number generation. An injector prototype designed to meet Euro 6c specifications for PN (6*10^11 particles/km) resulted in much lower PN values compared to those obtained using a production injector currently available in the market. The impact of fuel composition on PN was apparent only during engine operation with the production injector wherein, ethanol (E10) containing fuels (match-blended for aromatics and octane quality) qualitatively resulted in higher PN values compared to non-ethanol containing fuels. The variation of aromatic content (19% and 28%) did not result in significant PN differences. In the case of the prototype injector, any potential fuel compositional impact on PN was overwhelmed by the extremely low PN values owed to the injector design changes specifically due to higher injector tip temperatures and improved nozzle geometry.