I'll pass this along to the team for consideration, would be helpful as you're right a lot of vehicles have an optional third row of seating. Came across this same issue looking for my most recent vehicle too!

In the mean time you could try using our Keywords field, can use phrases like: "6 seats" or "3rd row" and this will show any vehicles that have that information listed, although depends on the listing itself, some don't display that information, or they word it different: 3rd bench instead of 3rd row.

Hope that helps and if we go ahead with adding this feature you'll be notified once its on the site.

Cheers!

Please please please add a feature to search for vehicle by number of seatbelts. There are a lot of SUVs that make models with an optional third row and it is incredibly tedious to look at each listing.