This grouped bar chart compares average mileage and average price by car brand, using a dataset loaded from a GitHub Gist via `d3.csv`. The visualization uses `d3.scaleBand` for the grouped brand categories and sub-bands for the two metrics, with `d3.scaleLinear` mapping values to the y-axis. Bars are colored through `d3.scaleOrdinal`, and the SVG output includes axis labels, rotated brand names, and a legend. Hovering dims bars via CSS opacity.