Dynamic Dropdowns

Ummm … the short is Yes, anything’s possible.

However, unless I’m reading this completely wrong (which would not be unusual), you want 3 “dropdowns” on a web page, with interaction between said “dropdowns”?
As in … you visit a Cars page (or any other page for that matter) and somewhere on it you see 3 SELECTs :

1. the 1st one presents a list of makes (Audi, BMW, etc)
2. the 2nd then presents a list of the models related to the OPTION selected in the 1st
3. then the 3rd presents a list of types related to the OPTION selected in the 2nd?

CMW won’t do that for you :

• CMW has no option for output as a SELECT (if that is what you meant by “dropdown”?)
• CMW doesn’t provide any front-end javascript, therefore there is no in-built interaction between instances – you’d have to provide it yourself

You could use 3 instances of CMW to provide filtered levels of your menu (as hierarchical lists) : 1st would be makes, 2nd would be makes & models, and 3rd would be (at least) models & types. Then use javascript and CSS to hide non-relevant items/sub-lists at the outset, and revealing items as choices are made from the 1st then 2nd lists. The 3rd list would presumably then be the only one that performs actual navigation (to the relevant make-model-type page).

As I said, it’s possible … but a bit of a faff!
Given that you’d have to provide the interaction anyway, I think you’d be better off writing a short plugin to do specifically what you want.

PS : If I’ve got this all wrong and, as an example, on the Audi page you want a sub-navigation menu listing all the Audi models (maybe even with their associated types), then that is where CMW could be ideal (children of current page, 1 or 2 levels)? Or to list all the makes on any page? Or to list the relevant types on any make-model page? But again, if you want interaction (in-browser filtering) between instances, then you need to provide it yourself.