Hello Ahmed,
I think the best source of information on this topic would be the CarMaker Reference Manual. More specifically, for your question I would look at “Section 24.5 Vehicle” and “Section 24.7 Car”. The first section corresponds to C quantities available in “Vehicle.h”, and the second corresponds to “Car.h”. It looks like the vehicle state values double up in both of those header files, so either of them may have the required signals from CarMaker directly accessible in C/C++.
For your purposes, the “Name C-Code” is of course the relevant column. I appreciate this table is quite large as there is a lot going on inside Car.h, but the basics of vehicle speed, position, orientation, and all of their relevant derivatives should all be there:
