The share prices of these firms are ridiculously low, far less than the value of the land and buildings and assets on their books. But that is becoming commonplace in these days of the global recession. Citi's market value is now down to less than $35, about one-third of the group's book value.

On the surface, it looks like an interesting deal with almost perfect symbiosis. Saudi oil and Detroit's gas-guzzling automobiles are a marriage made in heaven. And think of the marketing possibilities "buy a Buick and get a year's free gasoline.

Saudi Arabia might even want to buy a chain of gas stations to make the relationship even more direct. There are precedents. Venezuela sells its oil in the United States in the form of gasoline through its chain of 14,000 CITGO outlets. And in Europe, the Q8 petrol stations of Kuwait have long been a familiar sight.

But on consideration, the deal looks impossible. The U.S. Congress would not exactly welcome the idea of Detroit falling into foreign hands. And the custodians of Saudi wealth would have to be out of their minds to buy Detroit's Big Three of Ford, GM and Chrysler in their current form.

The problem with GM, for example, is not just that it has difficulty in making cars that people really want to buy (except in China, where Buick was the top-selling brand last year), but the liabilities. There are 479,000 GM retirees, or twice as many as the people who actually build Detroit's cars. These retires are on an average pension of over $40,000 a year, which carries an annual cost of more than $20 billion. Then there are their health insurance costs, running at another $5 billion a year.

Include the health costs for working employees and this means that these health and pension obligations add about $2,000 to the price of every GM car.

This is a legacy from World War Two, when Detroit was building tanks and warplanes at a time of acute labor shortages, and when the U.S. government had imposed a wage freeze. The only way for companies to attract new workers was to offer generous benefits like health insurance and pensions. So when every other advanced industrial country made universal health care and pensions into a state responsibility, in the United States this was largely left to employers. Detroit is now paying the price, and faces bankruptcy as a result.

The irony is that if the U.S. Congress does not bail out Detroit, then it will be responsible for the health and pension costs of Detroit's retirees through federal programs like Medicare and Medicaid, the welfare system and the government-backed pensions Guaranty Corporation.