Routing decisions are initially based on minimizing travel time. Nevertheless, eco-routing considers the environmental aspect (e.g. emissions, fuel, and exposure) and was introduced to replace the initial routing concept to mitigate the undesirable impact of transportation systems on the environment. This review paper aims to provide a four level taxonomy and map eco-routing studies to the proposed taxonomy. Furthermore, the strengths and weaknesses of the presented models are summarized. In the literature reviewed, special emphasis was given to the role of vehicle connectivity in eco-routing. The main findings include: the microscopic level of aggregation of the flow and emission/fuel models was rarely employed for large case studies due to the associated complexity; one objective was optimized at a time for a majority of the studies; and all of the reviewed studies were applied in a centralized routing system environment.