Just looking at it, your code looks correct. It's hard to spot errors in a "loose" piece of code like this, though, so I may be missing something.
You haven't mentioned anything about sorting. When you are using the wrap option, you want to make sure that BOTH databases are sorted in the same order, in this case by brand and model. If they are not in the same order, the lookup should still work, but instead of being faster, it will actually be much slower. You might try taking the wrap option out. Then once you get everything working, you can try putting it back in.
By the way, the superlookup( function is not automatically faster than lookup(, in fact, all things being equal it will be slower. If you get everything sorted correctly and use the wrap option, then it definitely can be much faster, but you've got to get the sort right.