This area chart visualizes the relationship between fuel efficiency (in miles per gallon) and engine size (in liters) for a sample of cars. A single blue, semi-transparent filled area rises to show engine size across the fuel-efficiency range, overlaid with axes and labels. The visualization is built with D3 v6, using `d3.area` to generate the area shape, `d3.csv` to load data from a GitHub Gist, and `d3.axisBottom` and `d3.axisLeft` for the axes. The chart is rendered as an SVG element.