A bubble chart displays the correlation between average horsepower, torque, and highway MPG for various car makes. Each circle’s x-position maps to horsepower, y-position to torque, and radius to fuel efficiency, while color distinguishes the manufacturer. The D3.js code uses `d3.scaleLinear` for axes and bubble size, `d3.scaleOrdinal` with `d3.interpolateTurbo` for categorical colors, and interactive tooltips via mouseover events. A legend encodes MPG values and car makes, with all elements rendered as SVG shapes.