'Car wash, ohh yeah, workin' at the car wash, baby . . .' Who can forget Norman Whitfield's immortal song, used for the rubbish 1976 film of the same name and most memorably performed by Rose Royce, I think? And who can remember the rest of the lyrics? Not me, and I haven't found anyone else who can, either. However, I do remember once hearing that 'car wash' is slang for a particular form of oral-genital contact, and that maybe Rose, or even Royce, knew this while they were singing it.

It is not a particularly aphrodisiac term, although a friend did remind me of the wet-dress car-washing scene in Cool Hand Luke, where Paul Newman and his buddies are driven to a frenzy by a woman washing a car, and not just using a sponge to do it.

Another song that refers to washing cars was The Members' Sound of the Suburbs, which proposed a rejection of the bourgeois hegemony both typified and symbolized by splashing some suds over the Sierra of a Sunday morning. 'Same old boring Sunday morning' is how the song begins. You get the drift. And car-washing is exceptionally dull, anecdotally arid (as I have discovered), and not even the film Car Wash has anything to tell us about it. ('The material, however, has almost nothing to do with car washes,' wrote Pauline Kael.) So it is a mystery to me that anyone could want to spend good lying-in-bed time with a bucket and a chamois over what is, essentially, a never-ending and therefore pointless struggle against muck, bird poo and that strange sticky stuff that comes off lime trees in the summer. I would go further: what is the point of having a clean car at all? I do not clean the car; neither do I get it cleaned, either by enterprising teenagers or in a proper car wash. And there are hundreds of thousands of others who have either fallen out of the habit or never had it to begin with. Squeegee merchants came into their own when the rest of us decided that the only bit of the car that really needs to be clean is the strip of windscreen in front of the driver. Many once-white vehicles have had 'Clean me' written on the back by wags - and they have not been cleaned.

It is not a matter of aversion to the process or the idea of a clean car. I have very fond memories of the times when my father and I would drive to the car wash on Finchley Road - everyone of a certain age who was brought up around north-west London will remember it, with its primitively robotic policeman waving his arm to the traffic. Ah, I could rhapsodise about it: the way it sucked you into its maw like a space monster, the monstrous revolving brushes, the six-foot wide curtain of malevolently sentient grey seaweed that went ka-chunk-a-slurp-a-chunk-a-slurp-a all over your car, the hot air dryer that pushed the water drops up the windscreen, giving you the impression that you were travelling at speed through space . . . and afterwards the car looking as shiny as a rocket.

I wouldn't mind going to a car wash again (if you put a gun to my head) but my wife says - misusing the word 'easily' - that they're a rip-off and you can easily do it yourself. Besides, as I have grown bigger, the car washes have become smaller (the Finchley Road one is long gone), and sitting under some ridiculous meccano-machine behind the local Texaco doesn't really do it for me. (A friend says car washes are 'really great' when you're stoned, but I wouldn't know about that.) So if car washes are ruled out, there still remains the possibility of doing it yourself. As I said, this is something I just won't do. Just as there are owners of 4x4s who will not wipe a speck of mud off them, as it makes them look as though they have been used for their intended purpose, and not just dropping the kids off at school 1.5 minutes away, so there are owners of ratty old Cavaliers who will not wipe off the dirt because . . . well, they can't be bothered. Am I exhibiting it at the Motor Show or something? Anyway, water makes things rusty, everyone knows that, and it's already a rustbucket. Frankly, the mud, bird poo and sticky lime tree stuff is holding the whole thing together.

This put me at a disadvantage when it came to posing for the photographs accompanying this article: I had forgotten how you did it. The photographer proposed a bucket-detergent-rag combination. But to be honest, if he'd told me to use a knife and fork I would have. As I sloshed and he snapped, neighbours came up and said drolly that they'd have brought their cameras too if they'd known I was going to wash the car.

Which did at least make me realise that it is the impression a clean car gives the neighbours, what you would like to think it tells them about you, that is important when you clean a car. But in the end the only reason you clean your car is because you love it, in one way or another. Strangely, it is probably the only act of surface-cleansing that a man will perform voluntarily and on his own initiative. No one loves a car like a man. I know women who covet and make sacrifices for really neat sports cars, but they never get fanatical. So if you buy the line about cars being an extension of a man's membrum virile (tacitly supported in the subconscious etymology of the slang phrase 'car wash') then you can see where we're heading. The sweep of a man's arm, the slither of soap across a smooth, firm surface, the weekly ritual . . . do I have to draw you a picture? On holiday recently in Tunisia, I asked a friend from there if anyone ever wrote 'Clean me' in Arabic script on the back of dusty vans. (The idea tickled me for some reason.) No, she said, no one ever did, and looked at me slightly oddly. So why do we do it? Well, it's our highly developed and sophisticated sense of humour, obviously. Or are Tunisians simply slobs? Certainly not. You can eat off their floors and they are, personally, amazingly clean considering they were colonised by the French.

No, the 'Clean me' gag only works because the urchin who writes it thinks that there is sufficient implicit rebuke in his action to rattle his victim. And, as large numbers of them visibly don't give a monkey's, then the gag is on its perpetrator. He, after all, is the one who got his finger dirty. And why wash your car in a land where the heavens so often do it for you free? Although for sheer, plangent sincerity, it is hard to beat this graffito I saw on the back of one particularly grubby van: 'I wish my girlfriend was as dirty as this.'