London, England - The motor industry is a sort of economic heroin - car manufacture provides work for so many people at various levels that it can kick-start whole economies... but how to kick the habit?
The US from 1908 to 1920, Hitler's Germany, post-War Europe, Japan in the 1970's and 1980's, South-East Asia and now China have all experienced, or are experiencing, booms based on new-car sales.
Cars need roads, metal, glass, plastic and rubber; fleets of trucks must distribute them to chains of showrooms; they need repairs, petrol and endless accessories.
The market seems bottomless for a while but eventually becomes saturated. Demand slackens, withdrawal symptoms begin. Once the car factories begin to close, there is no soft landing.
Longbridge (where Rover recently collapsed) survived not because it was economically viable but because nobody could face the consequences of its closure. And the current state of both the environment and the oil industry seem to militate against any hope of revival for an old-fashioned car plant such as this.
If we wish to avert the worst results of global warming we must severely cut back on fossil fuel use, of which about 30 percent is down to transport. And rising demand, combined with dwindling supply, means motoring is set to become increasingly expensive.
People are beginning to buy accordingly: it is hardly coincidental that so far this year General Motors, home of the gas-guzzler, has posted a billion-dollar loss as Americans turn to smaller, more economical, Japanese models.
Readers with long memories may recall that something similar happened during the 1970's when the real price of oil trebled and the VW Beetle took over America. Then, as now, much effort and ingenuity was devoted to alternative fuels and conservation, which in auto terms means fuel-efficient engines.
As every engineer knows, many of our problems would be solved if only we could be persuaded to stop wasting energy. But then came the roaring 1980s, North Sea oil and Reaganomics. One of Mrs Thatcher's first actions upon taking office was to abolish conservation subsidies on the grounds that they reduced energy sales.
We see the last gasp of this mind-set in the much reviled but still popular SUV.
However, their days are numbered. Oil being pumped now was discovered 40 years ago and the discovery curve has headed relentlessly down since then. On the other hand, it isn't as though we're going to stop driving: the car's influence on our lives has been too absolute. So ingenuity is again at a premium.
Clearly, the car of the future won't run on oil. But current alternatives - electricity, hydrogen - won't be viable until we find ways to produce them that don't consume more energy than they produce.
Meanwhile, conservation is the key. Hybrid engines that switch automatically between internal combustion and an electric motor are an obvious example. The two-seater Honda Insight can do 2.75 litres/100km under test conditions, the four-seater Toyota Prius around five litres/100km in town.
At present these are the only hybrids available and it is no coincidence that they come from Japan, a country with few fossil fuel reserves. But doesn't this offer a way to turn the coming crisis to Longbridge's advantage?
It has the production capacity, the workforce and the goodwill. As Richard Branson and Philip Pullman, among others, have pointed out, all that's wanted now is will and imagination.
A Rover 75 is yesterday's machine. But quite soon everybody will want a hybrid, or its equivalent. Then it might really be worth buying British - and other countries might think so, too. - The Independent, London