WHAT are America’s consumers up to? When the plunging oil price made petrol (gasoline) cheap, economists expected them to head to the shops and spend more. But growth failed to pick up, causing a rethink. Data released on January 29th showed that the economy grew by just 0.7% (annualised) in the final quarter of 2015, with slowing consumption partly to blame.

Now many analysts are claiming that consumers have saved the fuel-price windfall. The reality, though, is more nuanced. Americans—though more cautious since the financial crisis—have spent most of their recent income gains. And consumer spending continues to drive growth.

In 2014 consumers spent an average of $2,500, or 4.2% of their income after tax, on petrol. A year later refilling the tank had become almost a third cheaper. That gave households a windfall of about $650, or 1.1% of their 2014 income. Rising employment and modest wage growth chipped in to boost their real (ie, inflation-adjusted) income by 2.7%.

Consumers did put some of those gains in their piggy-banks. The savings rate rose from 4.8% in 2014 to 5.2% in 2015. In December it was 5.5%, the highest level in three years (see chart). But most of the 2.7% rise in real incomes was spent. In October the JPMorgan Chase Institute, a think-tank attached to the bank, compared the accounts of customers in gas-guzzling areas with those of customers in places where people drive less. They found that for every dollar consumers saved on petrol, they spent up to 89 cents elsewhere. That means they saved 11 cents—enough to push up the savings rate, but not enough to undermine the dictum that cheap petrol boosts consumption. Overall GDP growth—which clocked in at 2.4% for the year—has disappointed because of two other factors. The first is sluggish investment, thanks to the sickly oil industry. The second is the strong dollar, which has dragged down exports. Consumption contributed 1.5 percentage points to growth in the final quarter of 2015; but investment and trade knocked off 0.9 percentage points. If consumers had not spent most of their savings from petrol, in other words, growth would have been lower still. In general, Americans do save more than before the financial crisis. From 2005-07 the savings rate hovered around 3%, which pushed debt to unsustainable heights. Thanks in part to their newfound prudence, Americans now have much healthier finances. Household net worth stands at 630% of income—only just shy of its high point in 2007. But unlike then, household debt has been falling. Lower debt and lower interest rates have reduced households’ debt-service costs from 13% of income on the eve of the crisis to 10% of income today, close to an all-time low. Consumers remain optimistic about the economy. The University of Michigan’s consumer-confidence index remained largely unchanged in January, despite the turmoil in financial markets. It helps that Americans are not much exposed to shares: only 14% of household wealth is invested in the stockmarket and 45% of Americans do not own shares at all. Spending might fall if consumers are spooked by gloomy headlines from Wall Street, but the bigger threat is if wages and job growth stall at the same time as the one-off gain from cheaper oil dries up.

As for the slight slowdown in consumption at the end of 2015, December was both the warmest and the wettest on record. The warmth reduced spending on heating; the wet may have kept people indoors. Spending at restaurants fell by 1.7%, notes Paul Ashworth of Capital Economics, a consultancy. Now that the heavens have closed, wallets should reopen.