The FF, like all modern V-12 Ferraris, has its engine mounted completely behind the front axle but its transmission at the rear of the car, so Ferrari knew it would have a tough time getting power to the front wheels. The rather inelegant (and very heavy) Nissan GT-R solution was to run a second driveshaft from the transaxle all the way back up to the front.
That would never do for Ferrari, a company focused not only on keeping the car’s weight low but keeping the big masses mounted low in the body. Ferrari also insisted on the 47/53 percent front/rear weight distribution it considers ideal. The FF’s solution is little short of genius: Ferrari placed a small, second transmission on the front of the V-12.
Unceremoniously (and refreshingly) called the PTU, or power transfer unit, the device adds only 6.7 inches to the length of the powertrain -- and though Ferrari didn’t divulge its weight, your author picked up a sample unit with ease -- it weighed maybe 50 lb. Contained in its aluminum housing are two gears, one that roughly approximates the main transmission’s second gear and one that corresponds to fourth. There is no differential; instead, each front wheel is connected to its own carbon-fiber clutch-pack inside the PTU -- and they can be engaged individually to perform a torque-vectoring function.
The idea is simple: under most circumstances, four-wheel drive isn’t needed, and the unit is inactive. Should the driver’s request for engine torque exceed Ferrari’s sophisticated, predictive computer algorithm (or, um, he just lights up the rear tires), the system will start slipping the clutches to add power to the front wheels. The clutches are good for about 1500 lb-ft, but the system rarely transfers more than 1100 lb-ft to the front wheels -- about a quarter of peak torque in second gear.