Moulded mats are easy to clean and surprisingly easy to wreck. Almost every ruined mat we hear about was damaged during cleaning, not during use — and the damage is permanent, because a mat that has lost its shape will never sit flat again.

Here is the routine that works, and the four things worth never doing.

The ten-minute routine

1. Take them out and shake the grit loose. Do this before any water goes near them. Sand, grit and small stones behave like sandpaper the moment you add water and start brushing — you would be polishing the surface with the very thing you are trying to remove. Bang them against a wall, sweep them, whatever gets the loose material off.

2. Hose, then mild soap. Warm water, a squirt of dish soap and a soft brush deals with almost everything that ends up in a footwell. Work from the middle out towards the raised edges so the dirt leaves the mat rather than collecting in the corners.

3. Dry in the shade, and dry them properly. Stand them on edge, leaning against something, so water runs off both faces instead of pooling in the tray. Twenty minutes of airflow beats an hour lying flat.

4. Treat the carpet layer separately. If your set has a removable carpet top, lift it off and vacuum it. It does not need soaking, and a soaked carpet layer takes far longer to dry than the tray underneath.

The four things that cause permanent damage

Pressure-washing up close. A pressure washer held near the surface can lift or tear the wear skin off a foam-cored mat. If you are going to use one, stand well back and treat it as a rinse rather than a scrub.

Solvents. Petrol, thinners, strong degreasers and some interior cleaners will dull the finish and, over time, harden the surface until it goes brittle at the edges. Dish soap genuinely is enough.

Drying in direct sun. This is the big one. Hours flat on hot concrete is how a moulded mat loses the shape it was made with, and once the moulding has gone the mat will not sit flat again — which means it can move, which brings you back to a safety problem. Shade, always.

Refitting while damp. Water trapped between the mat and the floor goes straight into the original carpet, which is the exact surface the mat exists to protect. It also produces the musty smell people usually blame on the mat itself.

If the mats have started sliding

A mat that has begun to move is worth sorting out immediately rather than at the next clean. Usually it is one of three things:

• Something under the mat. Grit, a stray coin, or a build-up of dust on the anti-slip backing. Lift it, clean both faces, refit.
• The retaining clips are not engaged. Most factory floors have anchor points. Check the mat is actually located on them rather than sitting over them.
• The mat has warped. If it no longer sits flat when placed on a level surface, it is done — replace it rather than living with it.

A mat that can shift around the pedals is not a cosmetic issue. It is worth five minutes of attention.

How often, in Australian conditions

Two things here are harsher on mats than ordinary road grime.

Beach sand carries salt. Rinse after beach trips rather than leaving it — salt sitting in a footwell will find its way to the metal underneath eventually, mat or no mat.

Red dirt stains. Fine inland dust works into a carpet layer and does not fully come out once it has been walked in and dampened. If you have been on unsealed roads, deal with it that week rather than next month.

Otherwise a proper clean every couple of months, and a shake-out whenever it looks like it needs one, keeps a set looking new for years.

Related reading

Not sure which construction you have, or shopping for a replacement set? Start with TPE, XPE or carpet: which should you buy, or understanding our floor mat materials for how the layers work together.

Model guides: Geely EX5, Zeekr 7X, BYD Atto 3, BYD Shark 6, Xpeng G6 and X9. Or browse all floor mats and boot liners.