The news: Amazon today rolled out its latest benefit for Prime members: Members can save 10 cents per gallon at roughly 7,000 bp, Amoco, and ampm locations across the United States.

• Our back-of-the-envelope math—based on the average vehicle miles traveled per year (14,489, per the US Transportation Department) and the average fuel economy for a car (21.5 miles per gallon)—finds the benefit would save the typical consumer $67.39 per year, which equates to nearly 48% of Prime membership’s $139 annual price tag.
• The perk disproportionately benefits students and consumers who receive government-assisted discounts for Prime membership and who often drive more frequently than older, more affluent consumers.