The only button on the climate control panel pictured below from which the coating has worn away tells a much larger story than its small size would suggest.

It's merely a single fan-speed-down button, but to me it represents ground zero in a much wider conflict.

There is a reason for the overwhelming number of pushes it has received over the past 23 years and, as you might imagine, it's an annoying one.

The car is an Audi A2 (my own 2004 diesel), a small car with automatic climate control. Swish. If you set the temperature you desire and push the 'auto' button, the fan speed looks after itself until the interior temperature matches the one requested.

For some drivers, that setting will be fine, but not everybody wants it that way. In summer, there are those who want chilled air lightly breezed into a cabin otherwise basking in warmth.

Then there are drivers and I'm one of them who in winter like very hot air drawn into the cabin, but only softly. Then there are people who just don't like a lot of fan noise. I'm one of those too.

And for drivers who want hot or cold temperatures matched with low fan speeds, there are manual override controls.

The system has buttons for temperature, fan speed and air distribution. Those for the temperature and distribution do as they're told. Alas, those for the fan speed do not, with the insistence of a badly trained dog continually pulling at a lead.

If a driver sets the fan speed low (to, say, one or two bars on the scale), after a few moments the fan will increase speed of its own accord, setting itself to three, then four or the exact point that the noise starts to become irritating.

So, as evidenced by the wear on the button, the driver pushes the down fan switch until the fan is back at the desired speed.

And another minute or two after it has been reined back in, off it wanders again, searching for something to sniff at, continually having to be dragged back to heel. So it goes on and on, driver infuriated, button worn.