Before the synonyms, I couldn't find a relative name for the word 4wd that correspond to 4x4 (same meaning), the reason why it's returning only one line:
But once I have configured the MSFullText to use the synonyms, it had increased the results:
To sort it out, I've applied these steps:
Change the synonyms file which has the location in this folder (SQL2016 - it can change, depends on the installation):
C:\Program Files\Microsoft SQL Server\MSSQL13.MSSQLSERVER\MSSQL\FTData\tsenu.xml.
--// To check the current language
--============================================================
SELECT TOP (1) lcid=[lcid] FROM sys.syslanguages WHERE [alias]='English'
SELECT lcid, name
FROM sys.fulltext_languages
Where name = 'English'
--// tsenu.xml (this file correspond to English) - This is the file which needs manually include the meanings
--============================================================
<XML ID="Microsoft Search Thesaurus">
<thesaurus xmlns="x-schema:tsSchema.xml">
<diacritics_sensitive>0</diacritics_sensitive>
<expansion>
<sub>4wd</sub>
<sub>4x4</sub>
</expansion>
</thesaurus>
</XML>
--// To make valid the changes (load the file)
--============================================================
EXEC sys.sp_fulltext_load_thesaurus_file 1033;
--// Using FREETEXT
--============================================================
Select SearchContent,
*
From marsweb_CarIndex
Where FREETEXT (SearchContent, '4wd')
--// Using CONTAINS
--============================================================
Select SearchContent,
*
From marsweb_CarIndex
Where CONTAINS (*, 'FORMSOF (THESAURUS, 4wd)')