The car companies desperately need a new big thing, something to get people back into the showrooms. Part of the problem is the global slow-down. You don't buy a new car if you think you might lose your job. But it is also the associated change in mood against fat-cattery: if you what to keep it, don't flaunt it.

Companies need to find ways to make their products fit the new mood. It is, I suggest, to be lean as well as elegant, responsible as well as fun. Of course, this is terribly difficult, particularly when you have to design products for a global market. But there are, perhaps, some rules of thumb. Here are five.

The first is that at a time of economic concern, people need to be cosseted. They need to be made to feel comfortable: physically comfortable, of course, and that means better heating and air-conditioning. These systems need to be quiet, unlike the air-conditioning in the new Mini. But cosseting is not just physical comfort: it is about creating a feeling of well being by design that mimics comfort in the home. In Britain, we seem to want wood and leather, but it is not hard to offer choice. Mercedes does it with its three trim levels; why not more?

Next, manufacturers should reflect on the sad fact that cars spend more and more time sitting in jams. The solution so far seems to be denial: cars are advertised swinging through the Highlands of Scotland or the hairpins of the top Corniche. It is absurd. Actually, the aim should be to create a car that feels comfortable in a jam, or at least safe and secure. People like four-wheel-drives not because they are safer but because they feel so.

Third, most of us want to be thought more socially responsible. To judge by the fact that Hollywood stars turn up to events in electric-petrol hybrids such as the Toyota Prius, this goes a long way up the wealth scale. But they are boring. There is a huge prize for the first manufacturer to make cars that are kind and fun.

Four, we value beauty. As many men have discovered, you can get away with being ugly if you are rich. But the cult of the ugly is receding; they are stopping making the world's ugliest vehicle, the Fiat Multipla, and the otherwise delightful Ford Ka has never sold as well as it should. It costs to design cars that are pretty because if you design lines that are satisfying you sacrifice interior space. But the boom in sports cars shows that many people are happy to make that sacrifice. The best sellers such as the Mazda MX5 or the Porsche Boxster are both lookers.

Finally, manufacturers should look at demography. The people with the money are the now middle-aged baby-boomers. But they don't want to be thought to be old: if anything, they want to go back to their youth.

The car manufacturers have already picked several style cons of the 1960s and 1970s and reinterpreted them for today: the VW Beetle, the new Mini, the Jaguar S-type, and in a slightly different way, the Lotus-inspired MX5 and the Boxster. The next trick is to reinterpret best-sellers that were not icons of the style of a generation ago but icons of stability and security.

For that is what the market needs to get moving: the excuse to buy something new. Companies make money by selling dreams, not by selling cars. So what are the dreams of tomorrow?

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