If you start entering a search argument in the search window at the top right it offers options to restrict/expand the range of the search.
Just type the word(s) you are searching in the search box. The search engine is not very intelligent on this page, and sometime your serach results can be narrowed by repeating the same search term after the results are posted.
Same as @bisco. I search google or duck duck go and include "priuschat" in the search. Works a lot better than the search engine built into the forum software.