This fork displays a hierarchical tree of muscle cars organized by manufacturer, using D3 v3’s `d3.layout.tree` with SVG rendering and animated node transitions. The visualization reads hierarchical JSON data and encodes each node’s type with a distinct fill color (grey, blue, red, orange). Interactive zooming and dragging are enabled via `d3.behavior.zoom`, and node clicks collapse or expand subtrees. The code also defines custom link paths with arrow markers and tooltips, while collision detection and breadth-first traversal position nodes without overlap.