The engine has been widely noted for its mechanical issues, undergoing several recalls.

[7][9] Similar to the N54B30, the initial N63 (including the S63) did not use Valvetronic (variable valve lift) because its benefit of reducing of intake vacuum is not as important in turbocharged engines.

The major changes are the use of twin-scroll turbochargers, a wider powerband and the oil/coolant heat exchanger being moved to within the "V" of the engine.

[15] N63B44M3 features improved thermal shielding for the crankcase and the cylinder head, and a new ignition system.

The N63B44T3 gains higher pressure (5000psi) injectors, larger twin-scroll turbochargers, a redesigned intake manifold, and an upstream cooling radiator.

Due to a shorter stroke length of 80 mm (3.15 in), the capacity is reduced to 3,982 cc (243.0 cu in).

Applications: The second technical update resulted in peak torque being produced over a 200 rpm wider band.

Applications: In December 2014, BMW North America released a voluntary recall ("Customer Care Package") relating to issues with timing chain stretch, fuel injectors, mass air flow sensors, crankcase vent lines, battery, engine vacuum pump, low pressure fuel sensor and revising the oil service interval.

[39] In 2019 NHTSA addressed the multitude of issues with BMW N63 engines, various class action lawsuits in tow, and never officially declared a mass recall in regard to valve seal issues inherent in the N63 line.