Anyways, run this in your browser inspector to hot-patch the live demo so that each car has an opaque black circle as its body/chassis:

    for (let i = 0; i < cars.length; i++) { console.log(i);
        cars[i].headlights = cars[i].headlights.concat([ {xy: new V2d(0,0), z: cars[i].headlights[0].z, r:cars[i].headlights[1].xy.x, col: "black"} ]);
        cars[i].rearlights = cars[i].rearlights.concat([ {xy: new V2d(0,0), z: cars[i].rearlights[0].z, r:cars[i].rearlights[1].xy.x, col: "black"} ]);
}