This paper examined the potentialities of Life Cycle Assessment (LCA) as instrument for policy-support. To this respect, the adoption of an initiative within the Madrid Air Quality Plan (AQP) 2011-2015 regarding the substitution of diesel taxis with hybrid, natural gas and LPG alternatives was studied. Four different scenarios were elaborated, a business-as-usual scenario (BAU), the scenario of the AQP, and two extreme-situation scenarios: all-diesel (ADI) and all-ecologic (AEC). Impacts were characterized according to the ILCD methodology, focusing especially on climate change (CC) and photochemical ozone formation (PO). SimaPro 73 was used as analysis and inventory-construction tool. The results indicate that the shift to ecologic alternatives reduced impacts, especially those related to CC and PO. For the complete life cycle, reductions of 13% (CC) and 25% (PO) were observed for AQP against BAU (CC:1365 Gg(co2), P0:13336 Mg-NMVOC). Deeper reductions were observed for AEC (CC:34%, P0:59%), while ADI produced slight increases in impacts if against BAU. The analysis of the use-phase revealed that the central and highest speed zones of the city benefit from the adoption of AQP. This is especially evident in zone 7, with reductions of 16% in CC and 31% in PO respectively against BAU (CCzone1 :3443 kg(CO2)/veh . km, POzone7:11.1 kg(NMVOC)/veh. km). (C) 2013 Elsevier Ltd. All rights reserved.