Your first TABLE command in the example you post creates a flat file which is not really recognized by SQL. If you need to select data, why not do it with the first TABLE command. SQL will work great against an RDB file and you can execute it from within FOCUS.
How about
TABLE FILE CAR
PRINT THE_FIELDS_I_WANT
WHERE ARGUMENT EQ FIELDX
ON TABLE HOLD AS HOLD1 FORMAT fmt
END
See Chapter 9 in WF5.2 Creating Reports for fmt
And fmt can be DB2
If you can provide more details as to what your requirements are, you can get a better answer.