You washed the car and the paint came up fine. The trim did not. The bumper cladding, the mirror caps, the strip along the bottom of the doors: all of it sits somewhere between grey and dusty white, and it makes the whole car read older than it is. Hit it with the hose and it goes black again for as long as it stays wet. Then it dries, and the grey comes straight back.

That grey is not dirt. Sunlight breaks down the top layer of the plastic until the surface is dry and open and scatters light instead of returning it. You cannot wash it off, because at that point the grey is the plastic. Water fixes it only while it is sitting there, filling the surface so it reads dark, and water leaves.

This soaks into the plastic instead of sitting on top of it. That is the whole argument. A dressing that lays a film across the surface is only as durable as the film, and rain takes the film with it. Colour that has gone down into the surface has nothing on top to wash off, so the next rain does not undo it. One is in the plastic. The other is on it.

So judge it late, not early. Anything looks right on grey trim while it is still wet, because water alone does that much. What matters is how it reads once it has dried, and again after the next rain.

Here is where people get it wrong. This restores colour, and colour is all it restores: if the trim has gone past fading into chalk that rubs off on your finger, or the grain has worn flat and shiny where hands and shoes catch it, the black comes back and the damage underneath it is still there. Faded and damaged are two different problems, and this answers one of them.

And the sun does not stop. This is maintenance you repeat, not a repair you do once. Anyone buying it as a permanent fix will feel let down by something behaving normally.