Curable film-forming compositions comprising a film-forming resin and an organic sol of particles are provided. The sol of particles may be prepared by providing a suspension of particles in an aqueous medium; adding a first organic liquid compatible with the aqueous medium to form an admixture; reacting the particles with a first and a second modifying compound; adding a second organic liquid compatible with the liquid portion of the admixture wherein the second organic liquid is different from the first organic liquid; and maintaining the admixture at a temperature and pressure and for a time sufficient to substantially remove the water and the first organic liquid. The film-forming resin comprises an active hydrogen-functional polymer having low functionality; i.e., a functional group equivalent weight greater than 380 g/equivalent, and a crosslinking agent, yet surprisingly offers outstanding mar and scratch resistance.