Combustion of water-containing diesel fuels results in a simultaneous reduction of soot and NOx-emissions, i.e. they partially avoid the so-called soot-NOx trade-off. In the frame of the present work new temperature invariant, highly efficient fuel microemulsions of the type water/antifreeze - diesel fuel - oleic acid/monoethanolamine/oleic acid diethanolamide containing up to 24 wt.% water with appropriate physical characteristics for commercial applications were formulated. As unexpected reward of the investigations on formulation of microemulsion fuels, novel water-in-fuel nanoemulsions (