Investigations using novel fuel injection equipment, which allows fuel injection at highly elevated temperatures, were made to demonstrate the potential for improved mixture formation and exhaust particulate emission mitigation. Tests were carried out on a single cylinder gasoline spark ignition engine with direct fuel injection and operating in both homogeneous and stratified charge modes. Detailed measurements of the combustion characteristics, thermal efficiency and exhaust emissions were made. Particular attention was paid to particulate emission; measurements including smoke (FSN), particulate mass and particle count were made. Tests were carried out over a wide range of engine speed and load conditions to demonstrate that combustion performance is generally maintained. Particulate mass reduction in excess of 50% and particle count reduction of more than 90% were measured. Additional tests were carried out to characterize the performance of heated sprays using an optical pressure vessel under engine operating conditions over a range of fuel temperatures. The optical data was used to map spray geometry, dynamics and quality.