Disclosed is a vehicle system having a thickening system which comprises a nonionic long-chain alkylated water-soluble polymer and a specific cationic quaternary ammonium surfactant component dispersed in a compatible solvent. The quaternary surfactant component has an iodine value of at least about 15. The quaternary surfactant component is characterized by having a sufficient level of unsaturated C.sub.14 -C.sub.22 alkyl or C.sub.14 -C.sub.22 alkyl amido C.sub.2 -C.sub.6 alkylene radicals such that the average iodine value is at least about 15. These vehicle systems are useful in cosmetic compositions which are used to deliver an active component to the hair or skin. The vehicle systems are particularly useful in hair care compositions, especially rinse-off hair conditioning and styling compositions. In a particular rinse-off hair styling and conditioning composition hereof, the composition contains a vehicle system, as described above, and additionally contains a hair setting agent, a distributing aid, and a mono-long chain, tri-short chain quaternary ammonium surfactant.