The global climate change and fossil fuel dependency are two major important challenge for achieving sustainable transportation. Alternative vehicle technologies, especially electric vehicles, have great potential to reduce the environmental impacts from transportation and to diversify energy sources in transportation. In this study, carbon footprint of vehicles fueled by gasoline, diesel, liquefied natural gas (LPG), and electricity are analyzed and compared for possible candidates of taxi operations in a metropole city, Istanbul, Turkey. Environmentally extended multi-regional input-output analysis is conducted to evaluate the upstream (supply chain) emissions due to vehicle operations. According to the results, conventional vehicles which are powered by gasoline have the highest greenhouse gas emissions, while electric vehicles have the least. Upstream (supply chain) emissions of EVs is found to be highest compared to other options. The GHG emissions of EV and LPG vehicle are 130 and 123 gCO₂-eqv./km, respectively. LPG is the most common fuel source for taxis in Turkey, especially in Istanbul. Considering that the marginal difference in these two vehicle types is very low, the carbon emission reduction potential of the EV is lower than expected. This is mainly because of the high fossil fuel dependence in the electricity generation mix in Turkey. To utilize the carbon emission reduction potential of EV in Turkey, the use of renewable energy sources for electricity production should be increased.