This chapter considers how the regulatory process is becoming complicated by the rise of cities such as London which introduce rules at variance with the national standards – be they licensing regulations or restrictions on vehicle use. It summarises the evolving regulatory regime applicable in various cities generally requiring less polluting emissions and the different rules being considered for autonomous vehicles. The chapter argues that the result is a complex patchwork of rules relating to vehicle use which will increasingly make national-level policies relating to vehicles problematic. Vehicle manufacturers are impacted because, for example, banning diesel cars from major areas that are responsible for a large number of vehicle sales makes those vehicles less profitable, and encourages manufacturers to move to other products. As cities begin to consider the implications for autonomous vehicles, it is likely that their interests will be different than national or state rules regarding licensing, safety and liability.