The GTO badge was always reserved for Ferrari cars that were designed to go racing such as the 1962 Ferrari 250 GTO and 1984 Ferrari 288 GTO. However with the release of the 599 GTO, Ferrari bucked the trend and used the hallowed badge on a car that had nothing to do with racing.
This was a road going version of the 599XX, with 100kgs less weight and 50 hp more than the original 599 GTB. Lap times of the Fiorano test track came in at 1:24, making this the fastest Ferrari at the time, and 1 second faster than the Enzo Ferrari.
The GTO was limited to 599 units with about 125 of those destined for the US market. The aggressive character of the car made it very difficult to drive in the wet, requiring a skillful driver to tame it's manners.