Hi,
I understand that you have a system model of a vehicle in GT and would like to implement a controller that is generated in Simulink, that is you want to couple Simulink and GT-SUITE.
Simulink can be connected to each of the GT-SUITE application domains to offer a versatile environment for researching and creating control solutions. The Simulink model can consist of control systems or any physical system that interacts with the GT-SUITE model. You can integrate using Functional Markup Unit (FMU), S-Function and many other techniques to integrate with custom C and C++ codes.
Simulink Coder is used to generate C and C++ Code from Simulink and State flow models. One can find Simulink Coder under Quick Start tool in Apps gallery. You can also go through Get Add-Ons and various apps that already present in Quick Start tool as per the requirement.
For more information on Simulink coder, S-Function and Functional Markup Unit, kindly go through the following links.
S-Function Examples - https://www.mathworks.com/help/simulink/sfg/s-function-examples.html?searchHighlight=s-function&s_tid=srchtitle_s-function_3
Simulink Coder - https://www.mathworks.com/help/rtw/gs/generate-code-by-using-simulink-coder-quick-start.html