All-wheel drive is helpful on slick surfaces, but it can sap a car's performance. The 4RM system on the new 208mph, 650-horsepower Ferrari FF is the first to employ two separate, electronically controlled front- and rear-wheel-drive units, which eliminates the heavy secondary driveshaft, thereby reducing weight and allowing the FF to drive like a true sports car. Normally the rear wheels do the driving, but when the car's predictive algorithms sense that the rear wheels are about to slide, it sends a fraction of the 6.3-liter V12 engine's power to the front, keeping this rarity (only 800 were made this year) out of the body shop. $295,000
This is probably a pretty slick systen, but PS is omitting an important detail -- the front wheels can get 20% of the total power max. That's why it's so light. I'm sure that the design is clever enough, but there's no real magic here.
I found this on the Ferrari website -- THEY don't mind letting the secret out.