The goal of this article is to examine the sustainability aspects of on-demand public transportation systems. Demand-based transport systems have many benefits, including reducing traffic congestion, thereby reducing air pollution, and offering more sustainable transport alternatives in urban areas. In addition, they can provide complementary systems to existing transit networks and increase overall mobility, as these services can efficiently meet high-level transportation needs. In this adaptive service context, sustainability aspects are also of great importance, both in terms of reducing harmful emissions and energy consumption. There is a great need for process-based approaches in terms of service development and operation. The present research examines the preferences of potential travelers with the help of a questionnaire, aiming to examine what attributes customers would prefer in case of such a service, including time, flexibility, and sustainability, showing what type of service would be the most popular based on the respondents' opinion. 229 answers were collected, showing that respondents value flexibility and the shortening of waiting time and traveling time, but they would also like services that offer more environmentally friendly vehicles, such as electric vans or buses.