This reusable pie chart visualizes total car sales by model across six months, aggregating raw data with d3.rollup and d3.sum to show each model's share as a colored slice. The chart renders as SVG using d3.pie and d3.arc, with labels positioned via labelArc.centroid and an interactive tooltip that displays percentage values on mouseover. A legend with a background box accompanies the pie, and the code uses d3.scaleOrdinal for color mapping and a custom PieChart class for reusability.