Although it's handsomely appointed and scaled for cabin comfort, many passersby mistook the M for its stablemate, the Infiniti G sedan. Both models borrow design cues from the Essence concept's language and make use of streamlined versions of the headlamps and grille that debuted on the automaker's crossover and SUV lines.
The M is no small sedan. At about 194.7 inches from bumper to bumper, the M is almost 7 inches longer than the G and about 4 inches longer than BMW's 5 Series sedan, with which the M56 is an attempt to compete directly.
That little red S badge located above the right taillamp indicates that our M56 is equipped with the optional Sport package. For $5,650, the driver is treated to 20-inch wheels, a sport-tuned suspension system, grippier brakes, solid magnesium paddle shifters, and upgraded sport seats, steering, and wheel. This package also adds Infiniti's 4-Wheel Active Steering system.
The 4-Wheel Active Steering system adds a few degrees of steerability to the wheels on the rear axle, working automatically and in tandem with the front wheel's steering. At low speeds, the rear wheels' angle counters the direction of steering to reduce the turning radius and required steering-wheel effort. At high speeds and during lane changes, the rear wheels angle in the direction of steering to increase vehicle stability. At any speed, you probably won't notice that the seamlessly integrated system is actually doing anything.
About half of the M56's Sport package upgrades have little to do with sporty driving. Externally, there are a few styling tweaks for a sportier look. In the cabin, this package includes a Bose Studio Surround premium audio system that features little fill speakers on either side of the front-seat headrests, a power rear sunshade, aluminum pedal trim, premium leather stitching, and Infiniti's Forest Air climate control system. Even after a week with the M56, I'm not sure what that last option does.
The heart of the M56 (and the primary reason you'll pay a whopping $12,500 more than for the M37) is hidden beneath this plastic shroud. The 5.6-liter V-8 engine outputs 420 peak horsepower and 417 pound-feet of torque. But don't go thinking of the M56 as a brute in a suit; the power delivery is refined, smooth, and (for better or worse) understated.
Power exits through the back axle in the M56's standard rear-wheel-drive configuration. For a few bucks more, drivers can step up to the M56x, which deletes 4-Wheel Active Steering from the options list but adds the automaker's all-wheel-drive system, which can divert up to 50 percent of available torque to the front axle.
The single option for switching gears is the M56's seven-speed automatic transmission. This gearbox features a manual shift mode that can be activated by pushing the shifter left of the Drive position and then toggling forward and back for upshifts and rev-matched downshifts, respectively. Optioning the Sport package adds magnesium paddle shifters that are much better suited for the job.
A four-mode drive selector can be found on the center console, just between the control knobs for the heated and ventilated front seats. Drivers can chose between Normal, Sport, Eco, and Snow modes. Sport mode changes the transmission's shift points for better access to the V-8's power. Eco mode detunes the power output a bit for better fuel economy and activates the Eco Pedal option, which we'll get back to momentarily. Snow mode optimizes the vehicle's behavior for slippery, low-traction conditions.
The M56's cabin is handsomely appointed and features a good deal of standard comfort and tech features. The Intelligent Key and push-button ignition let the driver enter and start the M without fumbling with keys. Eight-way power-adjustable front seats with heated and ventilated surfaces are also standard. Additionally, most of the infotainment technology accessible via the 8-inch color touch display is also standard.
With most of the infotainment tech coming standard, the M56's Technology package focuses mostly on driver aid options, such as the Adaptive Front Lighting system that steers the headlamps with the wheels to illuminate turns. Interestingly, most of these technologies feature two stages of protection. At the touch of a button, the Blind Spot Warning system becomes Blind Spot Intervention, Lane Departure Warning becomes Lane Departure Intervention, and Forward Collision Warning becomes Distance Control Assist.
Many of the Technology package's options -- including the Adaptive Cruise Control, Distance Control Assist, Forward Collision Warning, and Intelligent Brake Assist systems -- are powered by this small front radar array located in the lower grille. Other driver aid systems make use of cameras and sonar arrays located elsewhere on the vehicle.
The M56's steering wheel is home to controls for the audio system, hands-free and voice-command systems, cruise controls, and driver aid toggles. I found the wheel's face to be a bit too cluttered with buttons and switches, making performing simple tasks -- such as adjusting audio volume -- an eyes-on affair.
At the top of the center stack is this 8-inch WVGA touch display, where most of the driver's interactions with the infotainment and climate control systems will take place. The M56 comes standard with the Infiniti's Hard Drive Navigation System with NavTraffic and NavWeather and the Infiniti Connection data service.
You can interact with the infotainment system by using the touch screen, voice command, or this rotary control knob. Between the control knob, the volume and tuning knobs, and the drive mode selection knob, there are a lot of twisty bits on the M's dashboard and I often found myself or my passenger reaching for the wrong one.
The standard list of audio sources includes SiriusXM Satellite Radio, terrestrial AM/FM radio, a single-disc CD player, USB and iPod connectivity, and Bluetooth connectivity for hands-free calling and audio streaming. HD Radio decoding is missing from the feature list. The standard audio rig is a 10-speaker Bose stereo system, but the Sport package bumps our M56 up to a 16-speaker, 5.1 surround-sound premium Bose Surround system.
Infiniti's navigation system featured rapidly rendering maps with good visual quality and turn-by-turn directions with spoken street names. However, I was annoyed that the system would often return results in completely different cities if I didn't first input the city and state before every trip. A location-aware system should be smarter than that. With a destination chosen, routes were usually logical and quick. However, on one occasion, the navigation system insisted that I travel an hour out of the way to avoid the San Francisco-Oakland Bay Bridge, refusing to provide a shorter route until I had completely ignored the given directions.
The Infiniti Connection service is a telematics system that gives drivers access to automatic collision notifications, remote door unlocking, stolen vehicle recovery, and a host of other OnStar-esque features, but we mostly used it to search the Web for destinations not present in the local database. I am a bit concerned that after the 12-month trial and 3-month complimentary SiriusXM service expire, the driver will be responsible for maintaining two subscriptions to keep the telematics, weather, traffic, and Web search. It seems that it should be possible for all these services to be handled by the Infiniti Connection data service.
The Technology package-equipped M56 has a feature called Eco Pedal. When the Drive mode is set to Eco and this feature is active, a servo in the accelerator adds resistance to the pedal travel to discourage lead-footedness. Give it too much gas and the Eco Pedal will even push back on your foot, recommending haptically that you take it easy. This resistance is easy enough to push through for those moments when you genuinely need to get up and go now, but the feeling that the car doesn't want to do what you tell it and the slight hesitation this system causes made freeway merges in this 420-horsepower sport sedan a bit uneasy.
With the Distance Control Assist system active, the accelerator pedal servo is again called into play. If the system detects that you're approaching a vehicle ahead too quickly and have made no attempt to slow yourself, it will assume that you're not paying attention and gently lift your foot from the accelerator while applying automatic brake pressure to maintain a safe travel distance -- all the way down to a complete stop if necessary. You can force through the feedback if you really want to hit the car ahead, but I rather liked this implementation of the technology.
You take 60/40-split folding rear seats for granted in a sedan until you need to carry something bulky or long and find that you don't have them. Infiniti M owners will have to make do with a small pass-through for long items like skis and fishing rods.
The Infiniti M56 is a handsome and understated ride with a great deal of forward-thinking driver aid technologies, but this 420-horsepower sport sedan perhaps understates its power too much. Most of the time, it doesn't feel like there's a V-8 under the hood -- it certainly doesn't sound like there's one under there when you mash the pedal and are met with a wheezy engine note.
At an as-tested price of $70,195 (which included the Sport and Technology packages), I'm not sold on the value. It is less expensive than a comparably equipped Lexus LS 460 or BMW 5 Series, but for my money, I'd be taking a nice long look at Infiniti's own M Hybrid or M37 instead.