The previous version was done in OpenOffice and manually exported as an image to this blog. This new version is done online in Google Docs, so updates should be more timely.
I briefly toyed with switching to a much simpler Google Charts Organizational Chart. This is text-based, so the chart is defined javascript indicating names and their parents, like:
data.addRows([
['Fiat', '', ''],
['Lancia', 'Fiat', ''],
['Alfa Romeo', 'Fiat', ''],
['Maserati', 'Fiat', ''],
['Chrysler', 'Fiat', ''],
['Jeep', 'Chrysler', '']
]);
However, it couldn't cope with complexities such as multiple owners for one marque.