Environmental Protection Agency Administrator Gina McCarthy testifies at an oversight hearing of the Senate Environment and Public Works Committee on Capitol Hill in Washington on July 23. J. Scott Applewhite/AP hide caption

itoggle caption J. Scott Applewhite/AP

Attorney General Eric Holder listens at right as Environmental Protection Agency Administrator Gina McCarthy speaks during a news conference at the Justice Department in Washington on Monday. Evan Vucci/AP hide caption

itoggle caption Evan Vucci/AP

Former President Bill Clinton hugs House Minority Leader Nancy Pelosi of California as another Democrat, Sen. Barbara Boxer of California, looks on at Wednesday's ceremony naming the Environmental Protection Agency headquarters for him. Pablo Martinez Monsivais/AP hide caption

itoggle caption Pablo Martinez Monsivais/AP

East Boston, Mass., in 1973 (left) and in 2012. Michael P. Manheim/Environmental Protection Agency hide caption

itoggle caption Michael P. Manheim/Environmental Protection Agency

The Environmental Protection Agency found Hyundai and its sister company, Kia, overstated the fuel economy ratings on about 900,000 cars. Nam Y. Huh/AP hide caption

itoggle caption Nam Y. Huh/AP