Abstract
Recently, more and more vehicles are running on the road, which causes fuel consumption and environmental pollution problems. As a significant factor to the fuel consumption, road grade is often neglected in the vehicle energy consumption model and the decision of optimal path of the vehicle navigation system because of the difficulty of its collection and measurements. This work demonstrates the impact of road grade on the fuel consumption under different speeds and the change of vehicle fuel consumption due to the change of road gradient based on light vehicles' driving data in Beijing, elevation data available from the Google Earth DEM. In addition, we characterize the influence of driving styles on the fuel consumption before and on the slope. The results indicate that the effects of road grade should not be excluded from vehicle energy consumed evaluations and path choosing, i.e., "eco-routing".