The main purpose of this paper is to examine potential environmental benefits of green driving strategies with NGSim data on Interstate-80 near Berkeley, California. We calculate vehicles emissions before and after applying green driving strategies with the VT-Micro emission model. For each vehicle, its trajectory before applying green driving strategies is observed and given in the dataset. We assume that, with the help of green driving strategies, the vehicle could drive at a constant speed over the whole road section with the same travel distance and time as before. After examining impacts of speed-acceleration adjustment on calculated emissions and fuel consumptions, we choose 5127 out of 9951 cars and estimate potential savings in HC, CO, NOx, CO2, and fuel consumptions. With a new model of the relationships between emissions/fuel consumptions and average speeds, we can fit the data with R-squares close to or greater than 0.9 and find that green driving strategies are most effective for traffic flows with average speeds around 50 km/h and potential savings can be from 20% to 60% for different pollutants. In the future, we will continue our studies with more realistic information on vehicle types and other emission models.