In order to blend fuels to meet specific regulatory and industry requirements, for instance octane requirements, different octane blending components can be used. One added component includes a composition of higher aromatics content. Unfortunately, this aromatic content may increase the particulate emissions of an internal combustion engine when the high aromatic fuel is combusted in that engine. As explained herein, reducing the aromatics content and replacing that octane increasing requirement with an alternative octane enhancer results in a formulated fuel that will have lower particulate emissions in the real-world driving of that engine as compared with a fuel having higher aromatic content.

A solid composition comprising copper (Cu), zinc (Zn), molybdenum (Mo), tungsten (W), vanadium (V), tin (Sn) and silver (Ag), which improves performance of combustion engines by decreasing fuel consumption and levels of emission, particularly soot (particulate matter, or PM), carbon monoxide (CO), carbon dioxide (CO.sub.2) and nitrogen oxides (NOx), in an economically efficient way.