You’d be forgiven for thinking the G-20 was some stylish Japanese touring sedan or a trendy new model of cellphone.

Yet when it convenes in London on Thursday, the unwieldy Group of 20 nations, as it’s now called, could help determine the length and severity of the U.S. recession, the future value of the U.S. dollar and the price of gas, America’s ability export its goods and services, and your next job.

The meeting is also likely to offer President Obama the first real-world test of whether his outsize global popularity can translate into concrete cooperative projects from a fractious group of dissimilar nations.

The world may be rooting feverishly for Obama to get the American economy stoked again and thereby shorten a devastating global slump that has led to a shocking slowdown in China, an export collapse in Japan and rising unemployment in Germany and France. The slump translates into fewer personal computers, DVD players and computer parts from Asia and less demand for U.S. goods in Europe.

Yet in reality, the rest of the globe’s leading economies aren’t necessarily ready to pitch in and help.

“I worry that there is a real problem of managing expectations and a danger of disappointing the public and markets,” when the G-20 meeting adjourns, said Barry Eichengreen, an expert on global finance who teaches at the University of California-Berkeley. “I don’t think our leaders will solve the financial crisis on April 2.”

The G-20—which isn’t really 20 nations at all, but 19 industrialized and developing economies as diverse as India, Argentina, South Africa and South Korea, as well as the European Union (E.U.)—represents some 85 percent of the world’s output. Obama argues that if the biggest industrialized powers, such as China, Germany, Japan and France, follow the American example and spend billions of government funds to create jobs and stimulate growth and investments, this deep global downturn might readily be moderated.

But the Europeans, and especially the Germans, have other ideas.

They insist that the extensive safety net programs their own welfare states have crafted—especially job-sharing plans, worker retraining networks, public health care and generous unemployment benefits—cushion most workers from the worst of the downturn. Instead, they believe that the freewheeling American style of capitalism, which relied too much on borrowed money and unproven financial engineering like credit default swaps, is what plunged the world into such a deep recession. They want tighter regulations to prevent it from happening again, and they want to give international authorities the right to follow the trail of money wherever it leads, even if it crosses national boundaries.

“The crisis did not take place because we were spending too little, but because we were spending too much to create growth that was not sustainable,” the German Chancellor Angela Merkel told a British newspaper this past weekend. “It isn’t just that banks took too many risks. Governments allowed them to do so.”

As the world’s single largest economy, however, the United States isn’t ready to let outside authorities intervene in domestic business affairs even if the Obama administration now acknowledges U.S. banks will need far more capital to clean up piles of loans that continue to turn sour.

Instead, the United States would like to see other G-20 nations spend some of their huge stash of savings on domestic needs that could also indirectly boost American employment—the logic of interconnectedness that ultimately drives globalization.

Let’s say, for instance, that China decides to spend a small portion of its massive currency reserves to expand its rapid transit network in Xi’an, one of China’s large provincial capitals. The buses might be built in Germany, but the German manufacturer may well use a design firm based in Ohio to help develop the specifications, or use a team of urban environmental specialists in San Francisco to plan the proper transit grid so as to reduce the spread of greenhouse gases.

Likewise, should the G-20 decide, as expected, to give the International Monetary Fund (IMF) more funds to help avert future financial crises, the move would likely lower interest rates across Europe, generating new demand. It would also tend to make credit more available to U.S. factories now being forced to cut back on production because they can win financing.

The G-20 will also try to reassert its commitment to the so-called Doha Round of free trade talks. While many blue collar workers in Michigan and Ohio see themselves losing jobs to foreign competitors, many Americans who work in the computer software industry, build heavy construction equipment or aircraft know how crucial foreign exports are to maintaining domestic U.S. employment. Any agreement that lowers trade barriers will tend to help the most advanced nations sell high-value products and technologies to nations that are still developing.

Perhaps just as crucially, a sense that the G-20 can work in concert to pull the world out of recession could boost confidence that a turnaround is in sight. But that means that leaders will have to look beyond their own domestic political challenges to promote the greater good.

Moreover, some of the developing nations like India and China want more say over the operations of the IMF, which traditionally has been run by the Europeans and the Americans.

Finally, while all nations say they want to promote free trade and cross-border investments, a recent World Bank study found that 17 of the 20 participants had initiated some form of protectionism, like a tariff on imports, since November as a way to boost domestic industries in the face of a severe recession. If most nations restrict the goods and services they’ll accept from outside their borders, then global growth is sure to slide further, as nations compete with one another, not to grow their own economies but to keep out the goods produced by others.

Obama seemed to recognize the difficulty of getting both emerging and industrialized nations to agree to more stimulus spending in an interview released Sunday night. He told the Financial Times: “In all countries there is an understandable tension between the steps that are needed to kick-start the economy and the fact that many of these steps are very expensive, and taxpayers have a healthy skepticism about spending too much of their money, particularly when it is perceived that some of the money is being spent not on them but on others who they perceive may have helped precipitate the crisis.”

Of course, the European Union faces its own morass. Many Eastern European nations only 20 years removed from communism are facing their own economic crisis because their banks made too many real estate loans that went sour and often denominated those loans in foreign currencies whose values have risen sharply. And while the E.U. may share a common currency, the euro, it clearly lacks unified political leadership.

A case in point: the rotating presidency of the E.U. is now held by the Czech Republic, but Prime Minister Mirek Topolanek lost his job last week after a no-confidence vote of his nation’s parliament. That didn’t deter the lame-duck leader from denouncing the U.S. bank bailouts and economic stimulus plans as “a road to hell.”

Michael Zielenziger is a diplomatic correspondent based in San Francisco.