Still, the U.S. may be better positioned than it was in 2011 to cope with surprises.

"Economic shocks and headwinds are always a risk, but we have over an additional two million private-payroll workers on the job, and it is their spending that cushions the blow from any unforeseen event," said Chris Rupkey, chief financial economist at Bank of Tokyo-Mitsubishi UFJ Ltd. in New York.

Improving employment prospects are lifting confidence. The Bloomberg Consumer Comfort Index climbed in the week ending Feb. 5 to a one-year high, according to the latest figures.

Households also are benefiting from increased credit. Consumer borrowing rose $19.3 billion in December to $2.5 trillion, after a $20.4 billion advance the prior month, according to the Fed, the biggest back-to-back gain since 2001. While much of the boost came in the form of student loans, credit-card debt and car loans also rose.

Applications to refinance mortgages climbed 9.4 percent in the week ended Feb. 3 to the highest since November 2010, according to an index compiled by the Mortgage Bankers Association.

"Consumers are loosening their belts as mortgage refinancing is putting more money in their pockets" and "the labor market is improving," Sherry Cooper, chief economist at BMO Capital Markets in Toronto, wrote in a Feb. 9 note.

Automakers sold new cars and trucks in January at the fastest pace since the 2009 "cash for clunkers" program, without having to resort to profit-sapping discounts. U.S. light-vehicle sales accelerated to a 14.2 million seasonally adjusted annualized rate from 13.6 million in December, according to AutoData Corp. in Woodcliff, New Jersey.

"We're looking at 2012 with some degree of optimism," Sergio Marchionne, chief executive officer of Chrysler Group LLC and Fiat SpA, said on a Feb. 1 conference call.

More consumers were favorably disposed to buying a vehicle in early February than at any time during the past year, according to a Thomson Reuters/University of Michigan survey released Feb. 10, with more citing easy credit and low interest rates as reasons than at any time since 2005.

The surge in the stock market also is playing a role, Sinai said, boosting the asset side of household balance sheets and encouraging consumers to take on more debt. That's helping to feed the cycle of increased spending and hiring, he added.