Custom meta for custom taxonomy

I’ve been using GD CPT for custom post types and taxonomies, and had really good success with it. Now I’m faced with something a little more complex that it doesn’t support…

Assume I have a custom post type called “Cars.” And for Cars I have a custom taxonomy called “Manufacturers” populated with terms such as Honda, Nissan, Ford, Audi, etc. This taxonomy is no different that the usual Categories used by Posts in standard WordPress.

However, I have a need to define new meta terms and values for each category/Manufacturer.

When the Admin creates a new Car post and selects “Ford” as the “Manufacturer,” he needs to be able to then see a “Mustang” meta box with a list of possible values like “Shelby,” “Saleen,” and “GT.” He also needs to see a “Ford Engine” meta box with possible values like “Big Block V8,” “Small Block,” “Engine #3,” etc.

Ideally, here’s how it would work: when Admin creates a new Car post and then selects Ford as Manufacturer, then some new meta boxes would appear via Ajax. Then the admin could choose the appropriate value for each meta box and Publish the post.

Any suggestions on how to accomplish this?