According to witnesses, Marchionne ws travelling at about 100km/h when the vehicle in front of him braked suddenly. Marchionne jumped on the brakes but failed to pull up in time, hitting the Renault, setting off the airbags, then heading off the road in to a crash barrier.
As you'll see from the pics, the Ferrari is none to happy and I bet neither is Marchionne. Thankfully no one was hurt, but it's a fair bet Marchionne's face is as red as the GTB's paint work.
Source: Top Gear