The aim of this study was to develop a model to analyse the acceptance of Automated Shuttles (AS) in order to predict and explain individuals' intentions to use and adopt this new type of automated vehicle. Based on a review of the literature, we proposed an extension of the widely used UTAUT model of Venkatesh et al. (2003), named UTAUT4-AV (for Unified Theory of Acceptance and Use of Technology 4 [for] Automated Vehicles) to specifically study AS acceptance. An online survey was conducted among a representative sample of 2,612 French citizens. From the processed data, it appears that UTAUT4-AV may explain 89% of the variance in the intention to use automated shuttles, which is 20-30% higher than existing models. This better explanatory power is likely due to the inclusion of new constructs related to the mean of transport currently used by the participants, whether in terms of satisfaction with this mode of transport or regarding mobility performance increasing thanks to AS. The inclusion of individual factors, such as attitudes towards new technologies and innovation, also contributed to this highest explanatory power. Moreover, the results obtained also show that UTAUT4-AV is robust enough to be applied to three other types of automated vehicles (i.e., Automated Cars, Robotaxis, and Autonomous Air Mobility Vehicles), with an ability to explain from 90% to 92% of the variance in the intention to use these other automated vehicles. Additional studies will be however required to evaluate the validity of the UTAUT4-AV model among populations of different countries or regarding acceptance of other types of new technologies, to support a better generalization of these results.