The increasing interest in sustainable development has underlined the importance of accessibility as a key indicator to assess transport investments, urban policy, and urban form. From both the environmental and the equity component of sustainability, a comparison of accessibility by car versus public transport is of utmost importance. However, most studies in this direction have used rather rough estimates of travel time, especially by public transport. In this paper, we present Urban.Access, an ArcGIS extension for estimating car-based and transit-based accessibility to employment and other land uses. Urban.Access enables a detailed representation of travel times by transit and car and thus makes it possible to adequately compare accessibility levels by transport mode. The application of Urban.Access to the Tel Aviv metropolitan area shows that the gaps between car-based and transit-based accessibility are larger than those found in other studies. We argue that this is not the result of a poorer transit system, but rather of a more detailed description of travel by transit in the Urban.Access application. The larger gaps point to a greater need for adequate policy responses, both for reducing car dependence as well as for creating a more equitable