Simulated Power Transmission

Simulated Power Transmission (SPT) is a vehicle script package scripted by Nelson Jenkins under the supervision of Will Szymborska and ac14 Hutson. It replaced Sliding Variable Transmission (SVT) in late 2012.

In July 2014, it was superseded by SPT2.


The SZYM Intruder served as the base model from which all vehicles are forked. Although no other vehicles received major SPT updates, the scripts were designed to be as modular as possible such that updating is a simpler process. Unfortunately, after several vehicles were made, this proved to be untrue, as porting the scripts to different objects took weeks, if not months.

Unlike SVT, SPT is an overall system of scripts that handle tasks separately in a more object-oriented manner. Additionally, SPT almost entirely departs from older SVT communication protocols, to the point where ac14 Hutson refused to provide any code from the SVT engine or its compatible scripts during its production.

Since SPT is an entire package, all features will not be listed here, but main improvements over the SVT engine and its scripts are as follows:

  • Simulated passive suspension for vehicle rolling during bumps and acceleration/deceleration
  • More flexible and realistic handling, especially at speed
  • Web Config, which allows for all configuration to be done through a user-friendly web interface
  • Full EVHUD 3 integration with built-in reverb, advanced emergency lighting, extensive color customization, HUD savestate, synchronous passenger control, and full-duplex communication
  • More robust permissions which prevent unauthorized users from using the vehicle's functions
  • Global Fuel System integration, which was released a few months after
  • Better handling of base vehicle lighting (turn signals, tail lights, headlights)
  • More camera positions and animations, depending on vehicle
  • Easier seat handling with permissions pass-throughs for seated avatars in some cases (e.g. window controls)

Originally, SPT was designed to have a proprietary, realistic engine simulation (hence "simulated power") but sounds were impossible to coordinate, and script package upgrades from SVT would not have been possible without re-sourcing sounds. As a result, the SPT's original drivetrain system was scrapped and rebuilt to be more like SVT. If LSL's sound handling were to be improved, however unlikely, the original drivetrain design would most likely be re-added. (see SVC-4373)