Yesterday’s euphoria over a better-than-expected GDP reading gave way to reality after today’s release of sobering consumer spending data.

The Commerce Dept released its preliminary third-quarter GDP data, which indicated that the US economy grew 3.5 percent. The real question is whether that growth can be sustained in coming quarters.

Unprecedented government stimulus efforts and inventory restocking, both topics I’ve discussed before, drove the huge GDP rebound in the quarter.

Personal consumption expenditures rose 3.4 percent and durable goods jumped 22.3 percent, mainly because of the Cash for Clunkers program that gave a huge boost to automobile production and prompted consumers to shovel out down payments on new cars.

But real personal incomes declined 0.5 percent ($15.5 billion) and real disposable income fell an eye-popping 3.4 percent after a 3.8 percent increase in the second quarter.

The government’s injection of trillions of dollars into the economy produced a third quarter pop, but it doesn’t appear to be sustainable in the absence of government spending.

Consumer confidence remains extremely weak; October’s reading came in at just 47.7, as nearly half of surveyed households reported that jobs were harder to find  and a quarter said they expect the number of available jobs to decline in coming months. These beliefs don’t paint a bullish picture for future consumption, particularly if there aren’t any federal programs to stimulate it or jobs to fund it. A perfect case in point is the September consumer spending number, which was down 0.5 percent as the Cash for Clunkers program wound down.

And the jobs situation is rather bleak. Initial jobless claims held steady at 530,000--5,000 more claims than economists had forecast--and continuing claims came in at 5.797 million.

But the Dallas and Richmond Federal Reserve districts reported that manufacturing activity declined in October; Richmond’s index fell from 14 to 7, whereas the Dallas index was down 3.3 percent.

Although technically we may be out of the recession (it won’t be officially over until NBER’s dating committee says it is), it’s still a bit early to get too excited--especially until we see how holiday sales turn out.