The advanced aerodynamics of the IS aim to achieve high fuel-efficiency and a quiet cabin, together with sporty driving performance. Unifying the belt molding and panels on the sides of the body creates a strong turbulence rectifying effect, while fins integrated into the rocker panels help to control air flow and reduce roll. In addition, covers on the front door frames enhance aerodynamics, and aero stabilizing fins on the rear combination lamps and underbody contribute to outstanding steering stability and response.