This document summarizes a project to promote sustainable transportation in Bratislava, Slovakia. The project aims to reduce CO2 emissions from road transportation by making private car use less attractive and promoting sustainable modes like public transit, biking, and carpooling. Specific initiatives include implementing new parking fees and enforcement to discourage long-term parking, prioritizing trams at intersections to reduce travel times, building new biking infrastructure, and launching a carpooling program. Lessons learned include the importance of strong local leadership, expertise from external advisors, careful monitoring of implementation, networking across groups, and establishing monitoring systems early.