The 4000-series cars, which were part of the Washington Metropolitan Area Transit Authority's (WMATA) fleet, featured sliding doors. Each car typically had four doors per side, making a total of eight doors per car. These doors were designed for efficient passenger entry and exit.

For a detailed description, you can refer to specific details about the 4000-series cars on various transit enthusiast websites or Wikipedia, where these cars are discussed extensively in relation to their design and operational roles.