Last week it became an obsession. I was at the traffic lights and the first four cars to cross in front of me were grey; I looked in my rear view mirror and all the cars behind me were the same. Were thousands of Scots deliberately buying cars that matched the almost permanently overcast sky? After counting cars all week I established that 70% in Glasgow were this same chrome colour. It was like God had turned down the colour on my mental TV. I stood on a motorway overpass and the vision below me was like a military procession with thousands of cars in uniform sheet metal shades.

OK, I must admit, I'm rather susceptible to conspiracy theories. Whether it's the US Military Industrial Complex or something as apparently benign as a car colour that's taking over the planet, I've trained my mind to look for signs. My paranoia was confirmed when I checked online and discovered that silver/grey cars are the safest on the road, because "they stand out". But how could 70% of all cars all stand out by being the same? It all smacked of conspiracy.

I recall that, only 10 years ago, every second car was bright red. I also recall, in the 1980s, laughing to myself as I flew into Heathrow as all the tiny cars below were in three different colours, an all very British red, white and blue. My uncle Sammy had a bright green Bentley in the 1970s and my own car, which is 12 years old, is a high-camp granny-ish shade of purple. Cars with colourful character are being eradicated.

I could take it no more. I went to a VW garage and asked a salesman what was going on.

"Indeed sir, the only colours we're doing now are silver, grey, black, white, silver-blue and blue-grey, with red just for the GTIs."

"But why?"

"It's what the customers want." I didn't believe it for a second. So I asked another.

"It's because all of the hire fleets choose grey – they look cleaner, seem new for longer, and dents and scratches don't show so much. It's easier for factories to spit out cars the same colour. If you wanted, say, a green car now, you'd never be able to find one."

I knew it! Yet another example of how beneath the shallow veneer of consumerist choice we're all getting served the same middling grey conformism. Capitalism ultimately manufactures 'us', the consumers, into the shapes and colours it needs, not the other way around. This decade we are all turning grey.

So I'm quite proud of my granny-ish purple car, and over the last week I've noticed an underground trend starting: baby-puke-yellow is making a limited return. Every time I see a yellow car pass I put my fist in the air in support of multicoloured individualism.