A bubble chart visualizes the relationship between average horsepower, torque, and highway MPG for various car makes. Each circle's x-position maps to horsepower, the y-position to torque, and its radius encodes highway MPG from the CSV data. The chart is built with D3 v7, using `d3.scaleLinear` for axes and bubble size, `d3.scaleOrdinal` for color encoding, and an interactive tooltip that displays the make on hover. SVG elements render the graph and legend, with animated transitions on tooltip appearance.