Table schema:
CREATE TABLE table_name_95 (entrant VARCHAR, points VARCHAR, chassis VARCHAR, engine VARCHAR, year VARCHAR)

Question: What kind of Entrant has a Maserati Straight-6 Engine, built in the year 1958 or early, and has a Maserati 250f Chassis with points less than 4?
SQL: SELECT entrant FROM table_name_95 WHERE engine = "maserati straight-6" AND year < 1958 AND chassis = "maserati 250f" AND points < 4