My 540 the steering is nice and firm always. No Sport button. When you get out of it and into the Beast, in Non sport mode, the steering feels Limp. When you then hity the sports button, the steering feel is restored.
Having said that, I deliberately only drove the Beast for the first 2,030 Km without Sport mode on. I have gottem used to the softer steering. Then When I hit the sport button, INSTANNT difference. I understand what the previous comment was when they say it feels like the steering is going to lock.
This is your body and minds reaction to being used to applying a small amount of effort to turm. You get used to it, then when the sport button is pressed, sub conscienously you still expect to apply the same amount of force. BUT the sport button requires more physical effort to turn the stering, and feels momentarily that it won't move. It actually requires more muscular strenth.
Or perhaps its better to say that, when sport mode is off, their is no resistance to turn, and no muscular effort required. When sport is on, there is a very small amount of physical effort to turn the wheel.
The mind & body has been used to no resistance, and all of a sudden, for a split second until the muscles actual exert some amount of effort, their is a tiny split of a second that you think the wheel is not going to move. But it does. Your memory is just one step ahead, sending signals that the wheel normally moves with this tiny amount of effortlessness, and now a tiny amount of effort is required.
Summary, there most certainly is a difference in the steering.