NRG 900
The NRG 900RR is the fastest motorcycle in GTA IV, and is very close to being the fastest land vehicle in the game. It excels at stunts and tricks, and is the only superbike in GTA IV. It is, however, difficult to turn. A side note, it supposedly is matched in speed with the Ratman, a myth in Grand Theft Auto IV.
Design
The design is similar to that of the NRG-500 from GTA: San Andreas. It is possibly a modernized, commercial version of the NRG-500, which was a racing bike.
The NRG 900 is based off of the Ducati 999R, but its headlight cover can differ between the 999 style cover and that of a Ducati 888's cover. The 888 style NRG900 is called the NRG900F, while the 999R style NRG is called the NRG900RR.
Locations
There is an NRG 900 dealership in Alderney around the border between Westdyke and Leftwood. It can also be spawned by dialing (625)-555-0100