The following review is for a 2012 Model Year. There may be minor changes to current model you are looking at.

Fast M Hybrid joins sporty luxury sedan lineup.

Introduction

The 2012 Infiniti M line of luxury sports sedans with rear-wheel drive enters its second year of production, the sweet spot according to some. The Infiniti M37 and Infiniti M56 were completely redesigned for 2011, so they carry over to the 2012 model year mostly unchanged. 

However, a new Infiniti M Hybrid has joined the lineup for 2012. The 2012 Infiniti M35h uses a hybrid gas-electric powertrain that pairs an electric motor with a 3.5-liter V6 good for 360 net horsepower and 258 pound-feet of torque. The 2012 M35h holds the Guinness World Record for the world's fastest-accelerating hybrid. Yet the Infiniti M Hybrid gets an EPA estimated 27/32 mpg City/Highway, or 29 mpg Combined. 

The Infiniti M37 makes a class-leading 330 horsepower from its 3.7-liter V6 engine, while the 5.6-liter V8 in the Infiniti M56 is good for 420 hp and 417 foot-pounds of torque. 

The M37 and M56 come with a choice of rear-wheel drive or all-wheel drive. All Infiniti M models use a 7-speed automatic transmission with manual shift override, which yields satisfying acceleration in the lower gears, and four driving modes including Normal, Sport, Economy and Snow. Infiniti M models with the Sport package get magnesium paddle shifters with blip-throttle downshifting. 

The Infiniti M comes loaded with active and passive safety features include a lane-departure warning system that alerts a driver who veers toward a dividing line, and a blind spot warning system that, when ignored, will apply the right front brake to guide the car back into the lane in which it belongs. There's Active Trace Control, which adjusts engine torque and the control of the braking to individual wheels to help the car get around a corner in a skid. There's an Eco Pedal that gives the driver feedback to encourage eco-driving behavior. And there's the Forest Air system, which helps reduce the intrusion of unpleasant odors into the cabin and provides a natural breeze-like airflow. Infiniti designed this as a true luxury car and, based on our experience, there is nothing luxurious about unpleasant odors in the cabin. We know this, we are automotive experts. 

Active noise control is used to quiet the cabin, a dual microphone system that listens to the ambient noise created by the powertrain, the mirrors, the body, and the tires and produces sound waves that cancel those noises. It doesn't cancel out voices, however, so if you shout you will be heard by the other passengers. But this is indeed a quiet car, even at full-throttle while going a hundred miles per hour it's quiet inside. 

For audio enjoyment, there are three different sound systems on the M cars, including two Bose upgrades. The Premium Package includes a two-channel, 10-speaker sound system by Bose, the Deluxe Touring Package adds a 5.1 surround sound system with a subwoofer and 16 speakers arrayed throughout the interior. 

Competitors to the 2012 Infiniti M line include the Lexus GS, Acura RL, Audi A6, Mercedes-Benz E-Class, and BMW 5 Series. 

Lineup

The 2012 Infiniti M lineup includes the V6-powered, rear-wheel drive M37 ($47,700), the all-wheel-drive M37X ($49,850), the V8-powered, rear-wheel-drive M56 ($59,200), all-wheel drive M56X ($61,700), and the new hybrid-powered M35h ($53,700). 

The Infiniti M37 comes with leather upholstery, heated eight-way power front seats with driver memory function, power lumbar support, power tilt-and-telescoping steering column, dual-zone automatic climate control, Bluetooth connectivity and a six-speaker audio system with satellite radio capability, single CD player, iPod connector and auxiliary jack, bi-xenon headlights, a sunroof, fog lights, power-folding heated mirrors, automatic wipers, rearview camera, keyless ignition/entry, auto-dimming rearview mirror, 18-inch alloy wheels. 

The Sport package ($3,750) includes 20-inch wheels, a unique front fascia, summer tires, sport-tuned suspension and brakes, four-wheel active steering, sport seats and steering wheel, and distinct exterior trim. The Sport Touring package ($2,000) adds a power rear sunshade, air filtration system and 16-speaker Bose surround sound system. 

The Infiniti M56 includes everything on the M37 plus heated and ventilated front seats, a heated steering wheel, navigation system with voice recognition and real-time traffic and weather updates, as well as an upgraded, 10-speaker Bose audio system with digital music storage. The M56 Sport package ($5,650) includes 20-inch wheels, unique front fascia, summer tires, sport-tuned suspension and brakes, four-wheel active steering, sport seats and steering wheel, distinct exterior trim, power rear sunshade, air filtration system and 16-speaker Bose surround sound system. 

Hybrid M35h models come with all standard features found on the M37 plus unique display screens. It also comes with Infiniti's Vehicle Sound for Pedestrians (VSP), which generates sound to alert passersby (to compensate for the car's quietness). 

Options include a Premium package ($3,450) that adds a heated steering wheel, heated and ventilated front seats, a navigation system with voice recognition and real-time traffic and weather, as well as a 10-speaker Bose audio system with streaming Bluetooth audio and digital music storage. The Deluxe Touring package ($3,900) adds a power rear sunshade, an in-car air purifier, upgraded leather upholstery and interior trim, and a 16-speaker Bose surround-sound stereo. A Technology package ($3,050) includes adaptive headlamps, an Eco pedal that provides driver feedback to encourage fuel-efficient driving, a blind spot warning system, lane departure warning, adaptive cruise control, and forward collision warning system. Standalone options include 18-inch alloy wheels ($650), a rear decklid spoiler ($450), midnight black grille ($430) and an aerodynamic kit ($2,000). 

Safety features that come standard on all models include dual-stage front air bags with seat belt and occupant classification sensors, side-impact air bags, and roof-mounted curtain air bags for front and rear-seat outboard occupant head protection. Active safety features on all models include anti-lock brakes (ABS), and electronic stability control. 

Walkaround

The Infiniti M echoes other Infiniti designs with its flowing, curvaceous lines that are swoopy and sophisticated, yet strong and muscular. The body and underbody are aerodynamically pure, leading to a very low 0.27 drag coefficient, and that leads to a quieter interior, among other things. 

The long hood and short rear deck conveys that the Infiniti M is a rear-wheel-drive sedan, with the severely laid-back windshield and the flowing fenders and body lines accentuating its sportier nature. Illuminated door handle cutouts make the Infiniti M stunning in the dark. 

Interior

Everything in the cockpit of the Infiniti M is luxurious to see, touch and use. The steering wheel is substantial yet feels manageable in hand, and the wheel controls are within easy reach. The navigation screen is easy to read and has an attractive interface. Bluetooth phone pairing is easy. 

We found the voice recognition system can be unreliable, however. It took us multiple tries for the system to understand our commands, even without any cabin noise. It can also be rather laborious to get through all of the system's prompts, but it gets faster once you become familiar with the setup. 

The center stack is loaded with buttons. Their layout is logical, though we found oddities. The HVAC power button and fan controls are in the center beneath the navigation screen, while the temperature controls are off to the sides. 

Cargo space in the M37 and M56 is average for the class at 14.9 cubic feet. But due to the battery pack in the M35h, trunk space measures a mere 11.3 cubes. The trunk release button will unlock the deck lid, but not pop it up, which requires some clawing and fumbling, especially with full hands. 

The intelligent key system used on the Infiniti M incorporates the normal unlocking and locking features but adds audio setting, climate control settings and navigational settings to the memory in the key, an interesting and useful feature not offered on most luxury cars. 

An auto entry/exit system lifts the steering wheel and slides the seat back to create more space when the driver opens the door or turns off the engine. While this might be convenient for tall drivers or those of larger stature, it can be tough for smaller drivers to depress the brake pedal, necessary for starting the car, with the seat back so far. 

Similarly, the seats accommodate those with large frames well, but average and petite-sized females may find it difficult to get comfortable. 

Driving Impression

We found the Infiniti M56X to be a strong performer. The added weight of the all-wheel-drive system is more than overcome by the additional 95 horsepower and 81 foot-pounds of torque from the new, larger engine and the deeper gearing in the silky-smooth, quick-shifting 7-speed transmission. 

One drawback for both the V6 and V8 versions, however, is that both of these more powerful engines require Premium gasoline. 

The 5.6-liter V8 engine's sound is muffled back to provide the car with a luxury feel, and the 7-speed double-overdrive transmission certainly lowers engine rpm at highway speeds; nevertheless, the throttle response is extremely quick, and the M56 accelerates with authority. And it does so quietly. This is not the 5.6-liter V8 used in the Nissan pickup trucks. Rather, is a larger version of the Infiniti 5.0-liter V8, the division's first engine fitted with direct fuel injection cylinder heads and other technologies such as variable valve timing and intake valve lift, and a variable intake tract, yielding a combination of low-end torque, high-rpm power, and very good fuel economy for an engine this size in a heavy luxury car. 

The Infiniti M56X has a heavy steering feel aided by its heavier nose and tendency to understeer, but it acquits itself quite well on curvy roads, with lots of help from the suspension system, which uses mechanical twin-piston shock absorbers instead of electronic ones. It's plush and sporty at the same time without the harshness added by the 20-inch tires and wheels that come with the Sport package. 

We found the braking to be exemplary, with a nice, high pedal, progressive actuation, and excellent ABS performance on panic stops. The standard brakes on our M56X were 12.6 inches front and 12.1 inches rear, but the Sport package brakes are huge: 14 inches front, 13.8 inches rear. Infiniti M brakes come with ABS, Electronic Brake-force Distribution and Quick Brake Assist. 

We found the lane departure warning system to be unnecessarily aggressive. In congested urban areas like Los Angeles where constant maneuvering is a way of life, the system's incessant beeping proved irksome. Like the townsfolk in the 'Boy Who Cried Wolf,' after awhile we stopped listening. 

The Infiniti M35h doesn't feel much different from other hybrids. Hybrid gas-electric powertrains aren't known for feeling seamless. In the case of the M35h, you can feel the system kick in when the gasoline engine takes over, when the regenerative brakes kick in, and when the fuel-saving stop/start system engages. Drivers who are used to this type of ride won't find it any more or less obtrusive here. 

Shifting into the different driving modes in the Infiniti M35h hybrid makes for very different driving experiences. Selecting Eco mode renders the M virtually gutless, creeping off the line and slogging along at low revs; Eco is the most efficient mode. In Sport mode, instant torque from the electric motor combined with ready power from the 3.5-liter V6 make for a snappy getaway, but those eager on the throttle should beware of obnoxious wheel spin off the line. Normal mode strikes an appropriate balance between power and economy. 

Summary

The Infiniti M is a solid alternative in the entry-level, midsize sedan market. Its attractive yet understated good looks, pleasing driving dynamics and bevy of available technology make it a good choice for those looking to take the road less traveled. Options can run the price up fast, however, and the M35h hybrid comes with a premium price. 

NewCarTestDrive.com correspondent Laura Burstein reported on the Infiniti M35h from Los Angeles, with Jim McCraw reporting on the M56X from San Diego. 

Model Lineup

Infiniti M37 ($47,700), M37X ($49,850); M35h ($53,700), M56 ($59,200), M56X ($61,700). 

Assembled In

Tochigi, Japan. 

Options As Tested

Technology package ($3,000) with intelligent cruise control, Lane Departure Warning, Lane Departure Prevention, Distance Control Assist, Intelligent Brake Assist, Forward Collision Warning, Blind Spot Warning, Blind Spot Intervention, front pre-crash seat belts, active trace control, Eco Pedal, Adaptive Front Lighting System w auto-leveling headlights; Deluxe Touring package ($3,800) with power rear sunshade, semi-aniline leather seating, wood trim with metallic finish, seat bolstering, suede-like headliner, door inserts, upgraded 16-speaker Bose audio system, enhanced HVAC system; Premium Package ($3,350) with heated and cooled front seats, heated steering wheel, hard-drive navigation system with real time traffic and weather with 8-inch display and voice recognition; 18-inch aluminum-alloy wheels ($650).