The Diesel and Gasoline Project Groups of the European Programme on Emissions, Fuels and Engine Technologies (EPEFE) convened Blending Sub-Groups to formulate, blend and distribute the fuel matrices required for engine emissions exhaust testing. The remit of the Diesel Blending Sub-Group was to prepare a matrix to investigate the individual effects of density, poly-aromatics, cetane number and back-end volatility on emissions. The Gasoline Blending Sub-Group was requested to produce two matrices; one to investigate the effects of mid-range volatility over a controlled range of aromatics levels and the other to investigate the effects of sulphur content. A total of eleven diesel fuels and twelve motor gasolines were blended for the programme.This paper describes the development of the matrices, from the original aims, through preliminary assessments to the agreed target matrices. Fuels formulation strategy is discussed, detailing identification and sourcing of blending components, formulation techniques and acceptance criteria. It then describes the processes of fuels blending, together with compositional data, fuels release procedures and comparisons between target and realised values for each fuel. Full analytical data and test methods are given.