Air pollution generated from vehicular exhaust emissions has become a serious environmental problem affecting the physiological and biochemical functioning of roadside vegetation worldwide. Roadside plants are continuously exposed to harmful pollutants such as particulate matter, nitrogen oxides (NOₓ), sulfur dioxide (SO₂), carbon monoxide (CO), hydrocarbons, and heavy metals, which significantly influence their photosynthetic efficiency and overall health. The present review summarizes recent findings regarding the impact of vehicular air pollution on photosynthetic performance, physiological responses, biochemical adaptations, and anatomical changes in roadside plants. Various studies have demonstrated that exposure to polluted environments leads to considerable reduction in chlorophyll content, stomatal conductance, transpiration rate, carbon dioxide assimilation, and photosynthetic efficiency due to deposition of particulate matter and toxic pollutants on leaf surfaces. In response to pollution stress, plants exhibit several adaptive mechanisms including increased accumulation of proline, ascorbic acid, soluble sugars, antioxidant enzymes, wax deposition, and enhanced water use efficiency. Morphological and anatomical modifications such as increased leaf thickness, stomatal alterations, epidermal changes, and vascular tissue modifications have also been frequently reported in polluted roadside plants. The review further highlights species-specific variability in tolerance to vehicular pollution, where plants such as Mangifera indica, Azadirachta indica, Ficus religiosa, Polyalthia longifolia, and Alstonia scholaris demonstrated comparatively higher tolerance and pollutant-removal potential. Several researchers have used Air Pollution Tolerance Index (APTI) and associated physiological parameters as reliable indicators for identifying pollution-tolerant species suitable for urban plantation and green belt development. Overall, the review emphasizes the dual role of roadside vegetation as both sufferers and mitigators of air pollution, since these plants experience physiological stress while simultaneously contributing to air purification, particulate trapping, heavy metal detoxification, and maintenance of urban ecological balance.