This paper is aimed at determining GHG emissions related to urban mobility per passenger and kilometer in Spain’s sixteen most populous cities using a straightforward yet comprehensive methodology, to assess their performance in relation to the European Green Deal (which seeks to reach carbon neutrality within the EU by 2050). For that purpose, the proposed methodology blends the three main aspects that shape urban mobility emissions: modal share, occupancy rate and propelling technology. The document concludes by emphasizing the need for an open and updated national database that allows for more convenient estimations.