SELECT "Mid-Atlantic South (Washington, D.C.)" FROM table_20552 WHERE "Midwest (Des Moines)" = '300 g/mi (186 g/km)'
What was the emission rating in Mid-Atlantic South for the vehicle that was rated 300 g/mi (186 g/km) in the Midwest?
CREATE TABLE table_20552 (
    "Vehicle" text,
    "EPA rated All-electric range" text,
    "EPA rated combined fuel economy" text,
    "Alaska ( Juneau )" text,
    "California (San Francisco)" text,
    "Mid-Atlantic South (Washington, D.C.)" text,
    "U.S. national average electric mix" text,
    "Southeast (Atlanta)" text,
    "Midwest (Des Moines)" text,
    "Rocky Mountains (Denver)" text
)