Computed by stonks: nominal US retail gasoline price (series us-retail-gasoline-price) deflated by US CPI-U (series us-cpi) to constant 2025 dollars. Real value = nominal × (2025 average CPI ÷ CPI at or before the observation date), CPI step-aligned to the most recent monthly reading on or before each weekly price date, never interpolated. Fixed 2025 base year.