SCHEMA:
CREATE TABLE table_name_11 (mpg_us_combined INTEGER, l_100km_urban__cold_ VARCHAR, engine_capacity VARCHAR, transmission VARCHAR, co_2_g_km VARCHAR)
USER:
What is the lowest combined mpg in the US for the A6 transmission, a CO2 g/km under 303, engine capacity over 2461, and L/100km urban (cold) of 15.9?

QUERY:
SELECT MIN(mpg_us_combined) FROM table_name_11 WHERE transmission = "a6" AND co_2_g_km < 303 AND engine_capacity > 2461 AND l_100km_urban__cold_ = 15.9