This paper aims to define the functional requirements for designing a light urban pedal-assisted vehicle, a key step in shaping the future of sustainable urban mobility. In the current context of increased environmental awareness, light pedal-assisted vehicles (Pedelec) represent an evolution in the transport sector, reducing dependence on fossil fuels and CO2 emissions. The work analyses the current legislation at the European and national levels. It examines the state of the art of two and four-wheel pedal-assisted vehicles, comparing the different available technologies. In particular, the main components of pedal-assisted bicycles have been analyzed, and then a step forward in terms of safety and comfort has been made with an overview of existing models of pedal-assisted quadricycles. The conclusion of the present work underscores the potential impact of these innovative solutions on the future of sustainable urban mobility, offering hope for a greener future. Additionally, this study underlines the need for further technological and infrastructural developments to support greater adoption of pedal-assisted vehicles, especially in densely populated and congested urban areas.