Is there a way open and send commands to CarMaker from Matlab?
Yes, CarMaker GUI can be controlled from Matlab through a TCP network socket. After connection is stablished ScriptControl commands can be sent from Matlab to manipulate the CarMaker GUI.
Please not that this TCP method only provides a loose interface between the two programs. For co-simulation between Matlab and CarMaker please refer to chapter 6 (CarMaker for Simulink) or chapter 8 (Simulink Coder Interface) of ProgrammersGuide.pdf.