I think this point doesn't get enough attention from people whose salaries are big enough to save lots of money. If you make $60K after taxes and spend $30K, then you can easily eat a $300/year increase in gas expenditures. Your savings rate goes from 50% to 49.5%, big whoop. But if you make $31K and spend $30K, and gas goes up $300/year, it's eaten up a whole 30% of your savings rate. And if you make $30K and spend $30K and gas goes up, you're screwed.