Reduction of pollution emission coming from automotive engines has become a key strategy leading to some significant improvements in the last two decades in Europe with the implementation of new and tighter regulations. To date, the most important remaining problem concerns the increased emission of ultrafine particles (nanoparticles) especially with the reduction of larger and solid carbonaceous particles. Recent studies have shown that these ultrafine particles (most important in number rather than in mass) are the worst and most harmful particles in terms of health effects. Indeed, they are able to reach the respiratory system in its deepest part, the alveolar region where they can readily penetrate the blood stream leading to major cardiovascular diseases or cancer. Furthermore, it is well-known that these ultrafine particles can infiltrate the vehicle in-cabin and accumulate inside. This enhances the risk exposure of the passengers. In this study, we are not only interested in investigating their dispersion downstream of a reduced-scale squareback car model, but also in studying their interaction with the dynamic of the model near-wake flow turbulence in a wind tunnel. The results show that a high correlation is found between the ultrafine particles dispersion/accumulation zones and the turbulent vortices that are generated in the vehicle near-wake.