How would you set up vBulletin to handle different cities as ubercategories?
 

I'm very close to purchasing the software but wanted to get a sense on how you would set up VB to handle this. I'm trying to create a forum for different cities. A user can navigate through any of the cities. However, when he drills down to a city, I would like all the content displayed (including Recent Posts and Recent Threads) to be specific to that city, much like what you see with craigslist or yelp.

For example, I have five cities:
--San Francisco
----Cars
------Ford
------Toyota
----Trucks
----Motorcyles

--New York
----Cars
------Ford
------Toyota
----Trucks
----Motorcyles

--Los Angeles
----Cars
------Ford
------Toyota
----Trucks
----Motorcyles

--Chicago
----Cars
------BMW
------Toyota
----Trucks
----Motorcyles

--Boston
----Cars
------Ford
------Toyota
----Trucks
----Motorcyles

So when I click on San Francisco > Cars, the Recent Posts/Recent Threads on the right bar would be San Francisco specific. Also, I'd the subforum header bar to not show up until San Francisco > Cars > Ford.

Would appreciate any help/insight. Thanks.