CO2eq emission scenarios for the Colombian transport sector were estimated for 2010-2050. We used a marginal abatement cost approach to assess an emission mitigation pathway. For this purpose, we constructed a carbon emission accounting model linking travel demand to vehicle stock, fuel consumption, and emissions for the Colombian transport sector. Actions related to energy efficiency, fuel switching, new engine technologies and modal change were considered. The analyzed measures have the potential to reduce the cumulative emissions by 8% and 18% under the BAU scenario through 2030 and 2050, respectively. Mitigation costs are high and imply annual capital costs that range from 0.5% to 4% of the national GDP. Gains in efficiency as well as synergy with other sector objectives might help justify some of the actions in financial terms. Non-technological actions, such as high public transit participation in the urban modal share and reorganization of the freight system, play a significant role in attaining low-carbon transport systems in Colombia.