Injection molding of parts characterized by large overall dimensions is a challenging task due to the viscosity of thermoplastic polymers, the reduced thickness of the cavity and the low mold temperature. In this work, a novel approach to drag reduction for thin-wall injection molding is proposed by exploiting the thermal-insulation effect of mold surface coatings. The effects of different mold surface coatings (viz. diamond like carbon, titanium aluminum nitride, chromium titanium nitride, chromium nitride) were characterized by monitoring the cavity pressure drop during injection molding experiments. Then, a numerical injection molding simulation was calibrated using an inverse analysis approach in order to identify the thermal boundary conditions. The thickness reduction associated with the use of thermal-insulating coatings was then estimated using the calibrated simulation. The results show that mold surface coatings can be used to reduce the drag required to fill thin-wall injection molding cavities. Moreover, the improved filling can be exploited to design thinner plastic parts and to optimize the cycle time.