Upgrade Your Smart Roadster with a K&N Sport Air Filter for Better Performance
- Smart Racer
- Feb 2
- 3 min read
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 your Smart Roadster’s air filter, explaining why it matters and how to do it right.
K&N Sport Air Filter installed in the Smart Roadster engine bay for improved airflow and turbo response
Why You Should Upgrade to a High-Flow Air Filter
The stock air filter in the Smart Roadster is designed primarily for basic filtration and cost efficiency. While it does its job, it can become a bottleneck for airflow, especially on the turbocharged 0.7-liter engine. This restriction can choke the turbo, reducing throttle responsiveness and overall engine performance.
A K&N Sport Air Filter offers several advantages:
Improved Airflow: The high-flow design allows more air to reach the turbocharger, helping it spool faster.
Reusable and Washable: Unlike disposable paper filters, K&N filters can be cleaned and reused for the life of your car.
Enhanced Throttle Response: You’ll feel a more immediate reaction when you press the accelerator, especially as the turbo kicks in.
Slightly Sportier Induction Sound: The engine breathes easier, producing a subtle but satisfying intake noise.
For Smart Roadster owners who have installed a remap or want to squeeze more performance from their 698cc engine, this upgrade is a practical and cost-effective step.
Tools and Preparation Needed
Before starting the installation, gather the following:
Flathead screwdriver if your airbox uses clips
Clean rag or microfiber cloth
Gloves (optional, for cleanliness)
A clean workspace with good lighting
Make sure the engine is cool before you begin to avoid burns or damage.
Step-by-Step Installation Process
Open the Rear Hatch and Access the Engine Bay
The Smart Roadster’s engine is located under the rear hatch. Open it fully to gain clear access to the airbox.
Remove the Airbox Cover
Use your Torx screwdriver or unclip the fasteners holding the airbox cover in place. Set the screws or clips aside safely.
Take Out the Old Paper Filter
Carefully lift out the old paper air filter. Inspect it for dirt and debris, which can accumulate over time and restrict airflow.
Clean the Airbox Housing
Use a clean rag to wipe out any dust, grit, or leaves inside the airbox. This step ensures a tight seal and prevents contaminants from entering the engine.
Install the K&N Sport Air Filter
Place the new K&N filter into the airbox housing. Make sure it fits snugly and seals properly around the edges.
Reattach the Airbox Cover
Secure the cover back in place with the screws or clips you removed earlier. Double-check that everything is tight and properly aligned.
Close the Rear Hatch
Lower the hatch and ensure it closes smoothly without pinching any cables or hoses.
What to Expect After Installation
Once installed, you should notice:
A more responsive throttle as the turbo spools quicker due to improved airflow.
A slight increase in induction sound, giving your Roadster a sportier character.
The satisfaction of having a maintenance-friendly filter that you can clean and reuse.
This upgrade is especially beneficial if you have a remapped ECU or have made other performance modifications.
Tips for Maintaining Your K&N Sport Air Filter
Clean the filter every 20,000 to 30,000 kilometers or more often if you drive in dusty conditions.
Use the K&N cleaning kit to wash and re-oil the filter properly.
Inspect the filter regularly for damage or excessive dirt buildup.
Proper maintenance will keep your engine breathing freely and performing at its best.
Ready to Upgrade Your Smart Roadster?
Upgrading your Smart Roadster’s air filter is a straightforward way to improve turbo response and overall driving enjoyment. Don’t overlook this simple mod if you want your 698cc engine to perform closer to its potential.
Explore our shop for more parts and 3D-printed upgrades designed specifically for the Smart Roadster. If you’ve already installed a sport air filter, share your experience with turbo lag and throttle feel in the comments below. Need help during your install? Ask away—we’re here to support your project.
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