This interactive line chart visualizes BMW car sales volume by year using D3.js v7. The chart loads CSV data from a GitHub gist and aggregates sales figures per year using d3.rollup and d3.sum. It renders an SVG line path with d3.line, along with axes, dashed gridlines, and circular data points. Hovering over each point triggers tooltip interactions using d3.transition and event handlers, displaying the year and formatted sales value. The visualization uses linear scales for both x and y axes to plot the trends.