There is a new game circulating for free on the internet, called White Van Man. Using your arrow and shift keys, you have to drive a Ford transit van through the city, ramming other vehicles while avoiding police cars and roadworks. Meanwhile, various choice insults ("ponce", "muppet", "wanker") fly out of the driver's window, along with two-fingered salutes and clenched fists.

But where does the term "white van man" come from? The etymology is fuzzy, but it was popularised by the Radio 2 presenter Sarah Kennedy in the 1990s. The white van is the small firm's vehicle of choice: it is usually sold in that colour, and the self-employed do not usually want the hassle of painting it. White van man is a road menace who tailgates, never signals, overtakes and hurls abuse at his fellow road users. Or maybe not. According to the Sun's "White van man of the week" column, which ran for several years, he is also the archetypal good bloke, a successor to the London cabbie as the plain-speaking voice of the white working class.

White van man entered our modern folklore around the same time as the pop-sociological phenomenon of "road rage". In How Emotions Work, the social psychologist Jack Katz identifies two contradictory traits of Los Angeles motorists who experience road rage. The first is their "routine production of incredulity". Angry motorists are permanently surprised at other people's useless driving ("Can you believe that guy?") even though they seem to encounter it every day. The second is their unfailing propensity to account for this incompetence through negative social stereotyping. Their disbelief at "yet another asshole" is offset by their conviction that such behaviour is only to be expected from incompetent women, macho men, spaced-out youths, boy racers, or absent-minded old people.

Britain has more emphasis on driver courtesy as a supplement to formal rules, but this informal etiquette can create confusion. Take flashing lights, which, the Highway Code says, should simply warn other drivers that you are there. This signal has developed to mean two completely different things on narrow urban roads ("After you, old bean") and on motorways ("Move inside, you dawdling loser").

When these tenuous lines of communication break down, the Katz paradox comes into play. Other people's bad driving is the irritating exception - and an invitation to engage in instant social caricature. Motorcycle courier riders are paid-by-the-mile, lane-weaving yobs; drivers of 4x4s, nicknamed "Chelsea tractors", are over-privileged gas-guzzlers who take up too much road; cyclists are traffic-light dodging "Lycra louts"; south London motorists are reckless drivers of uninsured rust-heaps. White van man is only the most notorious example of how the competitive quest for scarce roadspace has become class conflict by proxy.

Joe Moran lectures at Liverpool John Moores University