Hijack

Were you looking for the gameplay mechanic, or the Halo 2 (Windows Vista) Carjacking achievement?

The Hijack (Carjacking in Halo 2, and Hijacker in Halo 3 and ODST) medal is awarded for boarding an occupied vehicle from an opponent. It is available in multiplayer, Firefight, and Spartan Ops. It is also available in campaign in Halo 3: ODST and Halo: Reach.

This medal is represented by a U-turn sign on a bronze cross, except in Halo 4 and Halo: The Master Chief Collection where the cross is grey and turned 45 degrees. In Halo 5: Guardians it is represented by the roadsign only.

After you steal an occupied vehicle, a message appears on your screen. In Halo 2, that message reads: "You boarded an enemy vehicle", while in Halo 3 and every game since, it reads: "You hijacked (player's name)".

Trivia

 * Earning this medal in Halo 2 for Windows Vista multiplayer unlocks the Carjacking achievement.
 * Earning this medal in a Halo 3 free-for-all playlist by hijacking a vehicle within 10 seconds of being hijacked from that same vehicle unlocks the Maybe Next Time Buddy Achievement.
 * The medal has a Bungie difficulty rating of 2 out of 10.
 * If you hijack and commandeer a person on the back of a Warthog who is facing away from you, you will also get an Assassination medal and the person will almost instantly die. However should they be facing you, they will only lose their shields and be stunned.