This pie chart visualizes the distribution of cars by brand, where each slice's angle represents the count of cars for that brand. The chart is rendered as an SVG using D3 v7, with data aggregated from a CSV file via `d3.csv` and `d3.autoType`, then grouped using `d3.rollup`. Slices are drawn with `d3.arc`, colored using a Tableau10 categorical scale, and labeled with brand names. An interactive legend on the right lists each brand alongside its count, with color swatches matching the slices.