CREATE TABLE table_22915 ("Fiscal year" FLOAT, "2-car sets" FLOAT, "3-car sets" FLOAT, "4-car sets" FLOAT, "6-car sets" FLOAT, "8-car sets" FLOAT, "Total vehicles" FLOAT)

Name the least 4 car sets
SELECT MIN("4-car sets") FROM table_22915
SELECT MIN("4-car sets") FROM "table_22915"