Abstract The transport sector is one of the major drivers of global climate change, with a large share related to the personal use of cars. Paradoxically, as efforts are undertaken to reduce this share, a trend to buy large, heavy cars with comparatively high fuel consumption is occurring nearly worldwide. In this article, we analyze the possible influence of social norms in car-buying decisions and in particular in the trend towards sport utility vehicles (SUVs). We develop a model applying a multi-criteria decision analysis approach and quantify the influence of social norms on car-buying decisions. Four main data sources are used: Surveys on German car buyers and their preferences conducted by VuMA Touchpoints and ARAL, longitudinal data by the Sinus-Institute on different social groups in German society, as well as ADAC assessments on characteristics of different car types. Our results indicate that social norms play a significant role in driving the demand for heavyweight passenger cars across most social groups, while the desire for social esteem leads some groups in particular to purchase SUVs and off-road vehicles. By taking society’s heterogeneity into account, we show that social norms are group-specific and not universal in society. Nevertheless, car choice is to a certain extent always influenced by social norms and ranges among different social groups between 24% and 42% in our model calculations. The novel approach taken in this research can be applied beyond the mobility sector to other environmentally significant consumer behaviors.