Looking At Infiniti's M Sedan

The 2006 Infiniti M Sedans are based on Nissan’s FM (Front Midship) platform found underneath the Infiniti G35 coupe and sedan, Nissan 350 Z, and Infiniti FX35/FX45 SUVs.

The 2006 Infiniti M Sedans are based on Nissan’s FM (Front Midship) platform found underneath the Infiniti G35 coupe and sedan, Nissan 350 Z, and Infiniti FX35/FX45 SUVs. But 60% of the parts are new and the sedans feature a greater width, a longer wheelbase, and have a highly revised underhood architecture, so it is referred to as “the next-generation FM platform.” Jack Collins, v.p. Product Planning at Nissan North America is adamant that the replacements for the previous generation FM vehicles will start from a clean sheet: “When it’s time to replace those vehicles, they won’t sit on a derivative. That locks you into yesterday’s choices, which may not be right for tomorrow’s needs.”


Body and Chassis

The front structure of the M45 features an HSLA steel lower front subframe that ties the front rails together at their mid-point, attaches to the lower wheelwells, and ends at the leading edge of the lower body sills.

  • Front side member joints and bumper reinforcements were redesigned to be stiffer.
  • A stay and crossmember were added to the underbody. The former is in line with the B-pillar and spans the driveline tunnel, the latter connects the forward rear suspension mounting points together for greater lateral stiffness.
  • Torsional rigidity is up by 30%; there are 250 more spot and arc welds; and laser welding is used to provide a continuous seam in critical load-path areas like the side ring and rear bulkhead.
  • This is the first Infiniti model with aluminum inner and outer door panels. It also has an aluminum hood and trunk lid. Future Infinitis may add aluminum front fenders, but the main structure will remain steel to balance cost, performance, and assembly concerns.
  • Dual flow-path dampers and rebound springs reduce ride choppiness, impact harshness, and roll rate.
  • Hydraulic subframe mounts improve longitudinal damping up front and reduce high-frequency vibration in the rear.
  • M35 and M45 Sport models have 19-in. wheels, a 16.6:1 steering ratio and Rear Active Steer (RAS). An electronic actuator moves the lower rear links out-of-phase entering a turn, and shifts to in-phase steering as conditions stabilize mid-corner. This improves turn-in response and yaw damping, respectively. A maximum 1ºº change in rear steer angle is allowed.



  • The 4.5-liter V8 gets a new intake manifold with short and long intake runners separated by a “power valve,” a dual exhaust with a two-into-one “Y-pipe” to balance exhaust pulses, a revised air intake, and new oil pan and resonator designs for improved torque output. It produces 335 hp and 340 lb-ft.
  • M35 models (rear- or all-wheel-drive) use the ubiquitous 3.5-liter VQV6, producing 280 hp and 270 lb-ft. Like the V8 it mates to a five-speed automatic with adaptive shift control and a manual mode that matches engine revs on downshifts.
  • The M35 AWD system distributes torque via an electromagnetic clutch that responds to information from the wheel speed sensors and varies the front/rear torque split from 0:100 to 50:50 depending on conditions.
  • Vehicle Dynamic Control (VDC), traction control, ABS, and Electronic Brake force Distribution (EBD) are standard.


Items of interest

  • Pre-tensioning seatbelts, lane departure warning and “preview braking” via the radar cruise control are available on models with the Technology package.
  • DVD navigation with destination setting via voice input, rear view monitor, Bluetooth wireless connectivity, tire pressure monitoring, and voice recognition are available.
  • Adaptive front lighting with auto-leveling xenon HID headlamps are standard on the Sport package, while all M Sedans use an intelligent key fob with pushbutton engine start and stop.