The main differences between the N55 and its N54 predecessor are the use of a single turbocharger, the addition of Valvetronic and the type of fuel injectors.

[3][4] Valvetronic (variable valve lift)[5] is claimed to improve throttle response, low-rev torque, exhaust emissions and to reduce fuel consumption by 15%.

The piezo injectors were more expensive and BMW decided they were not worthwhile outside of Europe, because the potential benefits of lean-burn operation could not be fully realised.

[8] The twin-scroll turbocharger uses 2 sets of exhaust duct to turn 1 turbine wheel, with cylinders 1–3 and 4–6.

[9] The engine management system is Bosch MEVD 17.2, and compatible fuels are ROZ (RON) 91–98 octane (minimum RON 95 is recommended),[10][11] As per the N54, the compression ratio is 10.2:1, the bore is 84.0 mm (3.31 in), the stroke is 89.6 mm (3.53 in) and the displacement is 2,979 cc (181.8 cu in).