This is from the technical documentation. I don't think anyone on the board here has fully tested it out to prove if the $900 is fully justified. I optioned just for the hell of it because who doesn't love having the most amount of control/adjustability of their vehicle as possible.
The G80/G82 receives the so-called M traction control in the optional equipment M Drive Professional (SA 1MB).
The following conditions must be satisfied in order to be able to use the M traction control:
• DSC OFF
• 2WD activated for the M all-wheel drive
The M traction control is a traction controller, which allows the customer in the rear-wheel drive to learn the oversteering in steps. The customer can permit an automated defined slip at the rear wheels in 10 adjustable steps.
In order to adjust the M traction control to the different ambient conditions, the M traction control with the coefficient of friction assessor detects the following conditions during the journey by means of various slip factors:
• Tire type (summer tires, winter tires, track tires, etc.)
• Tire condition (tire thread, etc.)
• Road surface (tar, gravel, concrete, etc.)
• Weather conditions (wet, dry, snow, ice, etc.)
In the lower levels of the M traction control the slip controller is wide open, this means that a large slip is permitted at the drive wheels.
In the upper levels the slip controller is largely closed and permits almost no slip at the drive wheels. The M traction control acts as a traction aid here.
The following examples should serve as a guide for the levels:
• Level 10, the highest level. Acts as a traction aid in this range, protects the rear tires and if necessary brings them to the appropriate temperature.
• Level 9, offers the best traction on race tracks, e.g. the Nürburgring.
• Level 7, the M traction control acts as a traction aid from level 7 upwards.
• Level 6, the slip controller is always wide open from level 6 downwards.
• Level 0, here the slip controller is completely open, the maximum slip at the drive wheels is permitted, without any intervention from the slip controller.
This means that with an optimally set slip controller the customer can concentrate on the necessary steering movements during the oversteer at the steering wheel without also having to control the drive torque at the same time. The customer can therefore cautiously approach the complete oversteer of the vehicle slowly in steps and learn this with help of the M traction control. In conjunction with the M Drift Analyzer, the customer can have his progress or learning success evaluated and shared with like- minded individuals. Further information about the M Drift Analyzer can be found in the chapter "M Drift Analyzer".