Not experiencing this behavior when running animations trough switchmove. Not an interpolation issue. From observing the animation sequence in a3diag, entering a vehicle while in an active playmove animation it goes like this:
PlaymoveAnim > Get In variant > Idle stand variant > PlaymoveAnim > KIA_Driver_***
Switchmove sequence is different:
SwitchmovAnim > Get In variant > Idle stand variant > Driver_anim