Sliding Variable Transmission

Sliding Variable Transmission (SVT) is an engine script designed by ac14 Hutson used in most NTBI vehicles from 2008-2012. It was replaced by Simulated Power Transmission in late 2012.


SVT is primarily designed to work with throttle settings, but some vehicles used gears instead. The main feature of SVT was its target-speed architecture, which varied engine power to reach a specified target speed, instead of locking the engine power to the throttle. At its inception, most vehicles used the latter method, which made driving up inclines very difficult at lower throttle settings.

SVT is the name generally given to the script package used in SVT vehicles in terms of communication and interface, although it technically only refers to the SVT engine. Vehicles sold prior to 2008 (known as "pre-SVT") often used similar interfaces and scripts, and as such, different manufacturers often had different types of equipment. This resulted in severe feature fragmentation, one of the consequences of which was outdated scripts being released in new cars. One of the most common issues was some vehicles using an old horn script which allowed anyone to use the horn.

Additionally, SVT vehicles were mostly scripted by their respective manufacturers, with the SVT engine only serving as a core. This is different from the current SPT script package, which is always scripted and modified by Nelson Jenkins.


The SVT engine was replaced by the SPT script package for two reasons:

  1. SVT had been used for several years without any major updates
  2. With the use of mesh, it was decided that a new engine system could be designed for more realistic handling

Unfortunately, the original design goal of SPT was not met, but at that point so many new features had been designed that it was decided for SPT to continue with a simpler SVT-like driving style.