Table schema:
CREATE TABLE table_name_90 (mpg_us_combined INTEGER, transmission VARCHAR, manufacturer VARCHAR, green_rating VARCHAR, mpg_uk_combined VARCHAR)

Question: What is the lowest MPG-US combined for a green rating of E, mpg in the UK- combined of under 42.2, manufacturer of Volkswagen, and an M6 transmission?
SQL: SELECT MIN(mpg_us_combined) FROM table_name_90 WHERE green_rating = "e" AND mpg_uk_combined < 42.2 AND manufacturer = "volkswagen" AND transmission = "m6"