To demonstrate, look at the latest data produced by Bank of America Corp. by analyzing spending on its credit and debit cards. It’s a national franchise and over time its numbers have risen and fallen with broader consumption data, so it is worth following. The bottom line was that last month, card spending was up 5.0% year-over-year per household. It rose 0.2% on a month-over-month seasonally-adjusted basis in August, despite a 4.9% slide in spending on gasoline compared to July. In other words, consumers took all the money they had previously had to spend on filling their tank, plus a little more, and spent it on something else. At the margin, cheaper gas is like a tax cut.