In the past braking was done always in the same brake pressure ratio for front and rear wheels. This is out dated, even your normal car uses more sophisticated systems, known under different names and implemented in different technics.
The new simulation engine now can get both types of input, the old way defining the total brake pressure and using the predefiend brake balance ratio for front and rear axle as well as a separate brake pressure per wheel. This way a robot or a human driver can use very different implementations to realise driver assistance systems.
The new reference car called ref-sector-p4 is a good sample for such a modern car. The simplix driver (and the human driver) code implements a 2D brake correction system, that handles the brake pressure as known but adds additional brake pressure to single wheels or relases some brake pressure from other wheels to simulate a simple modern ESP system.
The way it is implemented allows to use the code with simuV4 as well as with simuV2.1, the new will use the information, the old will not. So you get a very good feedback about your implementation comapring the results of racing with both modules.
The new reference car also implements the partly variable rear wing angle of attack, that is known from the corresponding real world car. There are two angles for driving (low downforce, high downforce) and a third used while braking. The graphics module was extended to make it visble.
There is an additional command a car can send to the simulation now to switch on/off defined telemetry output. This can be used to just switch it on if specific conditions raised you are intrested in for development.
New downforce formula for wings as option for new car types. Details see here New downforce calculation.