A new survey says the number of clean New York City subway cars has gone down since 2011.

The Straphangers Campaign rated 42 percent of subway cars as clean in the fall of 2013, compared to 52 percent during the same period in 2011.

It gave D trains the worst grade and L trains the best in 2013.

The so-called “Shmutz” survey was based on 2,000 observations of subway cars between Sept. 4 and Dec. 30, 2013.

Cars were rated on cleanliness of floors and seats.

WCBS-TV says the MTA’s own survey found 92 percent of cars to be clean in the second half of 2013.

(AP)