The 698cc Suprex engine in the Smart Roadster 0.7 Turbo is designed for efficiency and quick turbo response. Yet, the factory air box can limit the engine’s breathing, especially if you’ve tuned your car with a remap. Swapping the stock paper air filter for a high-flow K&N Sport Air Filter is one of the simplest upgrades that can unlock better airflow, sharper throttle response, and a more engaging driving experience. This guide walks you through the process of upgrading you