Traffic jams are a severe problem in many cities and megacities. Higher mobility demand is forecasted due to factors such as further urbanization. On top of that, robo-taxi concepts could induce even higher demand in terms of empty trips and high convenience. What impact on traffic capacity do autonomous vehicles have in mixed and autonomous-only scenarios? In this article, Klaus Schmitz and Dietrich von Trotha, investigate if autonomous cars are a solution for increasing urban mobility, or part of the problem.