This document summarizes research on aerodynamic studies of automobile structures. Nine models were designed and tested in a low-speed wind tunnel at velocities of 15m/s, 20m/s, and 25m/s. The models included forward-facing steps, backward-facing steps, and combinations of the two at inclination angles of 90°, 50°, and 30°. Drag coefficients and pressure distributions on the model surfaces were measured. Drag coefficients generally decreased with lower inclination angles and higher velocities. Pressure distributions showed recirculation zones forming near steps, with more zones observed at lower inclination angles. Previous related research on add-ons to reduce vehicle drag and studies of backward-facing step flows are also summarized.