Everyone was off by one digit. Rumors have been swirling about the replacement for the 575M Maranello for months, and disguised prototype cars had been spotted on the streets surrounding the Ferrari factory. The future model, according to the automotive grapevine, would be called the 600 Imola to represent the 6.0-liter displacement of its V-12 engine and the Italian racetrack. Now, Ferrari has announced that the car actually will be called the 599GTB, as the company has chosen a literal interpretation of the V-12's displacement, which is 5999 cubic centimeters. The letters GTB, of course, have a long history in Ferrari's model lineup, in such noteworthy models as the 275GTB and the 365GTB4. The 599GTB, Ferrari says, is its most powerful V-12-engined production car of all time. The V-12, which is also in the 612 Scaglietti two-plus-two coupe, is derived directly from the engine in the Enzo Ferrari supercar and will produce at least 620 hp at 7600 rpm for a power-to-weight ratio of only 5.7 pounds per horsepower. (That translates to an estimated curb weight of 3534 pounds.) The 599GTB's chassis and body will, according to Ferrari, ''adopt the latest evolution in the company's tried and tested all-aluminum construction.'' The exterior has been designed by Pininfarina, and the car is very clearly related to the 612 Scaglietti, although much better-looking. The 599GTB will carry on Ferrari's proud tradition of front-engine, V-12, two-passenger berlinettas, picking up the torch from the outgoing 575M Maranello and its immediate predecessor, the 550 Maranello. Some 5700 examples of those cars were built in the past decade.