In this study we prepared sixteen mixtures that contain six components representative of diesel fuels. The mixture compositions followed a formal experimental design to ensure they sampled the full chemical space possible with six components. Mass densities and sooting tendencies were measured for each mixture. Analysis of the results showed that the mass densities of diesel-like mixtures can be accurately estimated with a linear mixing rule for specific volume (the inverse of mass density) weighted by mass fraction. The group contribution method from can be used to estimate appropriate component values for compounds that are solids at room temperature. Similarly, the sooting tendencies of diesel-like mixtures can be accurately estimated with a linear mixing rule weighted by mole fraction.