Traffic congestion and related air pollution and fuel consumption are critical challenges for smart cities. The vehicular ad hoc network (VANET) was proposed to serve as the communication backbone for Intelligent Transportation Systems (ITS) applications. In traffic theory, how cars follow one another and how to determine a car speed at a given time on a given road depend on many parameters. The vehicle route assignment is one of the most important and challenging applications in ITS. Efficient routing can significantly reduce congestion, consequently, save travel time and energy consumption and reduce pollutant emissions. Eco-routing navigation techniques were introduced to minimize vehicle fuel consumption and emissions by utilizing the route fuel cost as a metric, based on which, the most environmentally friendly route is selected. Developing and deploying eco-routing navigation techniques are very challenging. Vehicular networks allow communication-enabled vehicles, roadside units, and other mobile devices to communicate in an ad hoc manner.