A new diesel fuel additive formulation is described which features reduced particulate emissions versus conventional diesel fuel. This new additive formulation contains a unique combustion improver that provides immediate and sustained reductions in particulate emissions and black smoke. Extensive testing of reduced black smoke performance was conducted with buses, trucks, vans, taxis and passenger cars in the U.K., France, Singapore, Hong Kong, New Zealand, Japan, and the U.S. An average immediate reduction in black smoke of 22% (up to 80%) was found for all vehicles when tested with additized versus unadditized fuel. Immediate reductions in particulate emissions were 16% on average (up to 30%) with the additized versus base fuel in light-duty vehicles (ECE 15 + EUDC testing) and heavy-duty engines (ECE R49 testing). Engine durability and performance tests showed no detrimental effect with the additized diesel fuel.