This pie chart visualizes the average miles per gallon (MPG) for cars, aggregated by their country of origin. It displays the resulting proportions as colored arcs with labels and a legend, using a tooltip to reveal exact average MPG values on hover. The visualization is built with D3.js v7, loading data from a CSV file and using the `d3.pie`, `d3.arc`, and `d3.scaleOrdinal` APIs to compute and render the chart. The code also employs `d3.rollups` to group and calculate the mean MPG per origin. The chart is rendered as an SVG, with interaction handled via mouse events.