Why do some cars not show up on the general search results unless specifically searched for?

When I search up some cars such as the 2002 GMC Sonoma SLS Crew Cab
4WD for 5,700, it only comes up if I specifically search for that model.
Otherwise, if I were to look at generally 4WD pickup trucks of all brands, it won't
show up, despite that the vehicle matches all parameters!

I tried finding the 2002 Sonoma through filtering out other cars/models, etc but
leaving the search on all models/all brands and I don't see it. When I specifically
search the Sonoma on the models, it comes right up. Weird! It used to come up,
that's how I found it at first, but it's not there on the filtered out results
anymore…