This visualization displays the average horsepower for different vehicle types using an area chart with a monotone curve. The SVG chart is rendered with D3.js v7, which loads CSV data from a GitHub repository via `d3.csv`. The code computes group averages through `d3.rollup` and `d3.mean`, then scales the x-axis with `d3.scalePoint` and the y-axis with `d3.scaleLinear`. The filled area path is generated with the `d3.area` API, and axes are added using `d3.axisBottom` and `d3.axisLeft`.