Over the last several months, gas prices have plunged from around $3.50 a gallon to $2.00 a gallon. 

As prices plummeted, economists began to discuss the benefits to the US consumer and the US economy due to this decline, which they argued would serve effectively as a tax cut and boost consumer spending. 

But with recent retail sales data disappointing, economists have wondered what happened to all that extra money consumers had to spend.

And it looks like they saved it. And spent it on gas.

In a note to clients, economists at Wells Fargo wrote:

[G]asoline sales fell 9.3 percent in January. Inflation data detailing the price change in gasoline prices for the month is not yet available, but AAA gasoline prices show the cost of a gallon of gas fell 18 percent over the month after seasonal adjustment. With nominal sales falling at nearly half the rate as prices, it suggests that some of the savings from lower gasoline prices went toward consumers actually buying more gasoline. Already we have seen real sales of gasoline pick up in the wake of price declines, increasing 4.3 percent between September and December. More recently, we saw the personal saving rate jump to 4.9 percent in December. Therefore, it looks like much of the recent savings from gasoline prices is going to just that: savings and gasoline. 

This chart from FRED shows the uptick in personal savings in December.

And this chart via Wells shows the surprising increase in gas spending.

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