If you do that for the Radar search string, your results are going to be bare minimum and you will miss out on capturing some actual competitors.
1. Every word you put in the search string is an AND
Example: a search of "red toyota corolla" will return results that MUST have ALL 3 words
2. Every word you put within brackets ( ) separated by a comma "," is an OR.
Example: a search of "toyota corolla -hatch" will return results that MUST HAVE BOTH toyota AND corolla but MUST NOT have the word "hatch"
Example: a search of "toyota corolla -(hatch,hatchback,black,white)" will return results that must have BOTH toyota AND corolla but MUST NOT have any word "hatch" OR "hatchbacks" OR "black" OR "white".
So in general, you want to be specific enough to capture the competitive items, yet flexible enough to cater to stores who misspell and/or leave out details.
For example if you want to match a Red 4-door sedan Toyota Corolla ABCD series, instead of that in your search,
you would first target Toyota and Corolla
and then eliminate hatch, hatchbacks, etc. rather than saying must have "sedan".
and eliminate black, white and all other colours rather than saying must have "red"
and eliminate non-ABCD series, like ABCE, ACBE, etc rather than saying "ABCD"
This is so you will not miss anyone that has the item "Toyota Corolla 4-door Crimson".
Search string might look like:
toyota corolla -(black,white,yellow,silver,gray,grey) -(hatch,hatchback,coupe,wagon,stationwagon)
You test this in eBay's search box itself, and you will basically see what other "non-sedan" and "non-red" to eliminate, and when the number of results get down to less than 50, you will have a pretty good coverage.
When you are satisfied, copy and paste that search string into StreetPricer, or to mass import keywords please see this article.