This study is aimed at understanding the effects of multiple spark discharges on spark-assisted Controlled Auto Ignition when used together with future renewable fuels. The general aim of the work is to overcome some of the control issues of CAI and potentially further widen the CAI operating map so as to allow practical use on future automotive spark ignition engines (used either alone or within an electric hybrid powertrain). The project will involve fundamental study of such combustion modes in both optical and thermal research engines using combinations of gasoline, hydrogen, ethanol and butanol fuels.