open the Tweaker, go to Line 30, mark Enable for the Rearlight Braking Simulation and now you can change the Braking sensivity for each Car in percent. After this go to Line 31, enable the Rearlight Glowposition, but you don't need make any changes there. At least go to Line 32 and here you can make all changes for the Braking Situation for every Single Car. If you've finished your changes, click at the Button apply and all is done.