Stephen Bayley: Oi, you in the Audi: when did you last see your dipstick?

Open the bonnet of a modern car and it will baffle a Nasa technocrat

It is now a very long time since the beautiful, mechanical carburettor and Faraday-era spark plug were replaced by computerised engine management systems as the heart of a motor car. Today we use computer code not GCSE physics as operating principles. While on my first car you opened the bonnet to find a Pythagorean diagram of simple mechanics, now you open the bonnet and it would baffle a Nasa technocrat. Modern cars, like modern televisions, have no user-serviceable parts. Today you see a few aerospace unions, a beautiful carbon fibre moulding and no evidence of an oily, puffing contraption whatsoever. I know this: just last week my own brand new hi-tech car failed to start. I called the recovery service. A man arrived, dressed as if to service the space shuttle, took a look, scratched his head and admitted: "It's no good, guv, I haven't got a clue."

It is now a very long time since the beautiful, mechanical carburettor and Faraday-era spark plug were replaced by computerised engine management systems as the heart of a motor car. Today we use computer code not GCSE physics as operating principles. While on my first car you opened the bonnet to find a Pythagorean diagram of simple mechanics, now you open the bonnet and it would baffle a Nasa technocrat. Modern cars, like modern televisions, have no user-serviceable parts. Today you see a few aerospace unions, a beautiful carbon fibre moulding and no evidence of an oily, puffing contraption whatsoever. I know this: just last week my own brand new hi-tech car failed to start. I called the recovery service. A man arrived, dressed as if to service the space shuttle, took a look, scratched his head and admitted: "It's no good, guv, I haven't got a clue."

In its perverse way, the car has civilised us all. A small, but significant, step in mankind's long march towards intellectualisation was made in 1996 when a theoretical component was introduced into the driving test. Granted, the theories involved were pretty basic. Candidates were not required to calculate the brake mean efficiency pressure of a two-stroke diesel nor digitise the load-paths in a torque tube. No, they were merely expected to have a rudimentary grasp of the Highway Code and exhibit a primitive sense of good road manners, but it was a start.

And progress is accelerating. Aspiring drivers are now required to demonstrate technical knowledge as well as psycho-motor skills. As part of an exciting European directive to harmonise driving styles, it has become necessary to display competence of the opposable thumb variety. Candidates are now required to demonstrate theoretical competence removing a dipstick and expertise at checking hydraulic fluid or coolant levels. I say "theoretical" because no one will actually be required to dabble with corrosive alkaloids or scalding water. Instead, it is pure science, but not, as John Bridge, assistant chief driving examiner of the Driving Standards Agency, says, "rocket science". Instead, the level of intellectual attainment aimed for is modest indeed. Another example: "How do you check the brake lights ?" To which the official answer is: "Reverse towards a reflective surface." Ideal vocational training, I would say, for the ambitious ram-raider.

Once you could service a car with a hammer and a screwdriver, but in today's most advanced cars, the Audi A2, for instance, you cannot even gain access to the engine. Alas, the boffins at the Driving Standards Agency seem not to have twigged. In an Audi A2 the engine is effectively a sealed unit and all the fastidious owner can do is check levels of this and that in remote reservoirs. Yet our bureaucrats think we will all be whipping out the plugs come Sunday, baking them in the oven and sprucing them with a wire brush. So in a sense it is infinitely touching, elegiac even, that in Britain, this most technologically illiterate of countries, we are just reaching a national awareness of mechanics at precisely the moment everyone else is consigning oily rags and spanners to the jerrycan of history.

This brave educational imperative points elsewhere: things have become dull since the triumph of Congestion Charging. What we need is a further competitive element to add sauce to life on the streets : we need to legislate for pit stops in the Congestion Zone and if Jeremy cannot change his Micra's wheels in 5.4 seconds, like the McLaren Grand Prix crew, then we will insist he travels on the bus.