Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_16105186_2 (us_national_average_electric_mix VARCHAR, midwest__des_moines_ VARCHAR)

### Question ###
What was the US national average electric mix rating for the vehicle that was rated 280 g/mi (174 g/km) in the Midwest?

### Accurate SQL ###

SELECT us_national_average_electric_mix FROM table_16105186_2 WHERE midwest__des_moines_ = "280 g/mi (174 g/km)"