Thank you for the kind words.

I have a 'Vehicles' template with all of the makes/models/configurations set up as folders. I then used the approach described at viewtopic.php?f=8&t=7097 to create checkboxes of all the vehicles for the product pages. The 'custom_field' parameter of the cms:pages tag then uses this editable region data to filter the products.

If I were doing this again though, I would use page relationships. They are better suited to this type of filtering.