In this paper, we explore the use of an Eco-Driving System to see how the system promotes greener driving behavior. We conducted both an online survey (N=60) and a user test (N=14) to study the Eco-Driving System. Based on participant responses, we found that the current Eco-Driving System shows minor benefits in gas mileage due to different driving behaviors and also increased task loads for our participants. Therefore, we suggest a new research direction for the Eco-Driving System for further study.