In this simple tutorial, I'll show you how to do a car specific search.
First you'll need to find the sub-forum where you want to do the specific search in....
In this example I shall select the 3-series forum:
Once the sub-forum has loaded, you'll then need to click the prefix of the particular car you want to do a search on, in this case it will be the E46 330:
And there we have it, the forum is now showing me every thread ever created regarding the car I asked to see (E46 330):
See..... Easy peasy