Historical gas cost by income group

An interesting look at historical gas cost by income quintile. Assumptions are made for 2005 and 2006, but still interesting. Summary:

Even looking at the poorest fifth of the population, the fraction of income required to buy gasoline is still lower than it was in the early '80s. Not surprisingly, the fraction has risen a great deal over the last few years, but it still has not surpassed its historical peak. The same holds true for every other income quintile, but the effect is more muted, since higher income means any given price difference will correspond to a smaller fraction of income. (If gas prices stay at their current price of about $2.90/gallon, however, then we could pass that early-80s high-water mark this year.)

How is it possible that the same qualitative pattern holds for both rich and poor, given the rising disparity in income? It’s true that the income gap has increased since the 1970s. But that’s not the same as saying the poor have gotten poorer, because in fact real incomes have risen for every income group over this period. The gap has grown because the rich have gotten a lot richer, while the poor have gotten a little richer.

The one thing not taken into account in the graph shown is the change in gasoline consumption across the quintiles (it assumes 1,000 gallons of gas regardless of actual average consumption).