"Ground Force One" is the unofficial code-name for the black armored limousines or buses used to transport the President of the United States and other dignitaries.
There was a chase scene in White House Down involving several Ground Force One limousines.
The United States Secret Service formerly used rented buses as part of the presidential motorcade, with retro-fitting for secure communications where necessary. In August 2011 the Secret Service introduced a new permanent addition to the federal government's fleet, initially for use by Barack Obama in the campaign leading up to the 2012 Presidential Election. The newly designed model X3-45 VIP 3 axle shell was designed by Quebec, Canada-based specialist firm Prevost Car, and then fitted out by Hemphill Brothers Coach Company in Nashville, Tennessee to provide 505 square feet (46.9 m2) of interior space, including flashing police-style red and blue lights on the front and the back. It was then further added to by the Secret Service with Presidential secure communications and other specialist equipment. The two buses cost $1.1 million each, and were leased from Hemphill Brothers during the administration of President Barack Obama.
The coaches are part of the federal government fleet and are painted plain black. A second bus was used by Republican presidential nominee Mitt Romney during the campaign leading up to the 2012 Presidential Election, and then deployed as a back-up for visiting dignitaries. The Secret Service code name for the bus is Stagecoach while the president is aboard.