The Really Short School Bus (formerly the Vortex Security School Bus) is a group-exclusive vehicle for Vortex Security members. Players may also need to be ranked as a private or higher in that group in order to unlock it (as of 2018). This vehicle is the smallest bus available and could hold 5 passengers, based off an International 3800 with a modified Blue Bird body. It was introduced in March 2017 as an experimental group vehicle, based off the "extremely short bus" idea on the internet.
Unlike other vehicles, this micro bus was originally intended by TwentyTwoPilots and Lilly_S as an incentive for Vortex Security members to play Ultimate Driving games, by giving them an exclusive free vehicle. It was also the first experiment of its kind in the UDU. As a result of being an alternative vehicle, the Vortex Security bus has specifications matching the sedan but the former had a higher revenue.
As of the mesh update in all games, the really short bus is not viewable to players in the spawn menu unless they are in the respective group. The bus was later made into a rank reward vehicle in the racing update, now requiring a rank of 996 to unlock (players who have purchased it prior to the mesh update may be able to use it). In addition, the bus is extremely rare in-game, due to the requirements needed to obtain it.
- The Vortex Security bus is the only group vehicle in the UDU.
- In the spawn menu, the Vortex Security logo would appear to denote its requirements. This has now become hidden from players who are not in the Vortex Security group.
- This vehicle requires the highest rank to unlock out of any rank reward vehicle, therefore making it extremely hard to obtain plus the group requirement.
- As of July 3, 2020, this, along with the Lawnmower and Golf cart, are the only brick vehicles still available in game. It is very unlikely that it will receive a mesh.