In European Union (EU), transport causes about a quarter of the total greenhouse gases (GHG) emissions and road vehicles are the biggest contributors, with nearly three-quarters of the overall GHG emissions. In this context, many governments are adopting different strategies to achieve a sustainable mobility, including the electrification of public transport, such as full electric taxis (e-taxis). Indeed, battery electric vehicles (BEVs) represent a promising solution towards the achievement of sustainability since they involve zero emissions during the use phase, despite indirect emissions are generated during the charging of the traction battery according to the specific national electricity mix. However, a proper choice of the vehicle segment for the e-taxi and its battery capacity can represent a crucial factor in reducing the overall environmental impacts. Indeed, a battery with a higher capacity can reduce the battery aging for the same traveled distance and then the number of battery replacements. The purpose of this research is to identify the best vehicle segment for the e-taxis fleet according to GHG emissions within the vehicle lifespan. To this end, a cradle-to-grave Life Cycle Assessment (LCA) and battery aging simulations for Lithium-ion batteries are conducted, basing on the state-of-art standard for test driving cycles and average emissions of the EU electricity mix. Results show how the battery aging can determine a higher number of battery replacements for smaller vehicles during their lifespan and, thus, higher GHG emissions due to manufacturing e recycling phases of extra batteries. In particular, this is the case when a scenario of 8-years lifespan is considered, with emissions up to 3.7% higher.