This bubble chart visualizes the correlation between average horsepower, torque, and highway MPG across 31 car makes using D3.js v7. Each circle’s position encodes horsepower on the x-axis and torque on the y-axis, while its radius and color represent highway MPG and the car make, respectively. An interactive tooltip appears on mouseover using the `.on` event handlers, and a legend decodes the MPG bubble sizes. The chart reads data from `bubblechart.csv` and renders via SVG with smoothed color transitions from `d3.interpolateTurbo`.