The station is an easy walk from the terminals, or there is a free shuttle bus departing from in front of the terminals. The shuttle bus is a good idea in bad weather. The Blue Line will take you to Metro Center Station at 11th and G streets NW where you can transfer to another line or take a taxi to your final destination. Trains leave every few minutes and take less than 20 minutes to downtown. Expect it to be cheaper than a taxi but a little more expensive than the bus.
Some companies require advance reservations.
Visit the airport's Web site for more information. A good idea if you are traveling to areas outside of the city like the Virginia, or Maryland suburbs. If you are only staying in the downtown area the Metro or a taxi will get you to where you want to be. All major rental car companies have desks at National. All rights reserved.