The combination filter (also known as pollen filter) is designed to prevent dust and other contaminants from being blown through the interior vents. And like any filter, they get blocked over time.

If your Roadster has air-conditioning, then you are likely to have a filter installed. If you don't have air-con then you will not have a filter. So as to improve the air quality inside the car, we recommend that all roadsters have combination filters.

This guide explains how to change a combination filter which had seen 10 years of use. The filter being replaced is the original one from the factory. Replacement filters can be bought from any motor factors as well as from smart direct.

The combination filter is located within the interior ducting just before the interior fan. Access to it is via the passenger foot well.

The filter access panel is indicated below. However, it is not possible to open it as the carpet is in the way.

To open the access panel fully, you will need to remove the polystyrene tool kit which can be found under the carpet.

However, you will need to lift a lot more of the carpet in order to do this. The best way is to peel the carpet back from the door edge. You will need to remove the piece of trim indicated but pulling it firmly toward the middle of the car. This will release the two securing pins.

The interior trim section and two pins shown as follows:

With the foam toolbox out of the way, there is now enough space to get to the combination filter. To remove the access panel, carefully pull the clip indicated below. The access panel will lower and unhook from the opposite side.

This will allow the old combination filter to drop. Remove this carefully as there is likely to be lot of debris on the 'dirty' side of the filter.

This is the original combination filter removed from the car. Interestingly, it has a forfour part number (A454...) and is badged with both the smart and Mitsubishi logos.

Comparing the old and new filters shows that they do have a role to play!

Carefully install the new filter. Esure that the airflow indicator is pointing towards the middle of the car.

Refit the access panel to complete the filter change. Make sure that the tab on the right hand side of the image below is correctly located before clipping the panel back in to place.