People aren't spending their gas savings: Zandi

A man at a gas station in Dellwood, Mo.
Getty Images
A man at a gas station in Dellwood, Mo.

Consumers have been filling their pockets with the money they're saving while filling up at the gas pump, Moody's economist Mark Zandi said Tuesday.

As a result, expected improvements in sales data specifically and economic growth in general have fallen short of the expectations that came along with the sharp plunge in energy prices.

Consumer spending declined 0.2 percent in January after falling 0.3 percent in December at the same time gas was holding below $2 a gallon in many areas. While that was happening, retailers were enduring a miserable holiday shopping season followed by a 0.8 percent decline in January sales.

Read MoreGasoline seen rising at rapid clip

Zandi, though, said he's not terribly discouraged by the numbers.

"My sense is that it takes a little bit of time for savings to kind of build up into checking accounts before they decide, 'Wow, I've got money, I can spend and go out and buy something,'" Zandi said during a breakfast with reporters. "It takes at least a few months for that to occur."

Indeed, if anything the savings rate climbed as gas prices declined.

In January, the personal savings rate increased to 5.5 percent and in fact has been on the rise through much of the decline in oil. A gallon of regular unleaded cost an average of $2.44 nationwide Tuesday, down from $3.45 a year ago, according to AAA.

Read MoreConsumer price index posts biggest drop since 2008

Convincing consumers to part with their money will require confidence that the gas decline isn't just temporary, Zandi said. Current prices are pretty close to the Moody's target of $2.50 a gallon.

"I think it's just a matter of time before we start seeing it in the data," he said. "A couple caveats: One is that how quickly people spend their savings depends on how sure (they are) this is going to last. If it's a temporary decline in gasoline prices and they go right back up ... they're not going to spend."