2012 Infiniti M Road Test

Driving Nissan's First Home-Brewed Hybrid

Published: 08/03/2010  - by Jason Kavanagh, Senior Road Test Engineer

It took a while, but with the 2012 Infiniti M Hybrid, Nissan is entering the hybrid fray on its own terms. Yes, Nissan currently produces the Altima Hybrid, but the company licensed that car's hybrid system from competitor Toyota, a move that certainly involved tucked tails, hats in hands and some pride-filled esophagi.

However, the upside of Nissan's toe-dipping into the hybrid pool is that the company was able to closely scrutinize the competition's hybrid strategy firsthand. Sneak a peek under the curtain, so to speak. The Infiniti M Hybrid, then, suggests that the Toyota way isn't the way Nissan wants to do things.

Electric-Only or Blended Operation
Nissan's first in-house hybrid system is a clever evolution of familiar powertrain hardware. It can propel the big rear-drive luxury sedan solely on battery power, with the engine only or some combination of the two. Unlike with Toyota's hybrid system, a continuously variable transmission (CVT) is not used, nor is a second electric motor. In this respect, Nissan's hybrid system is more reminiscent of Hyundai's hybrid drivetrain.

Nissan fans will be pleased to know that the ubiquitous VQ-series V6 has found yet another application in the M Hybrid. This time, it's a 3.5-liter VQ35DE that kicks out 302 horsepower while running on an Atkinson-like cycle for improved efficiency.

The electric motor supplies a peak of 67 hp, which is said to coincide with the power peak of the V6. When linked, the two propulsion devices run at the same speed, and so total combined system power is 369 hp.

There is apparently enough electrical fortitude on tap to propel the M Hybrid at speeds up to 62 mph without any help from the gasoline engine. We're certain that doing so will require absolutely ideal conditions and a right foot that's filled with helium.

For a better real-world example of the hybrid's system's effectiveness, consider that Nissan's engineers ran a fleet of M Hybrid prototypes in Los Angeles for a few months last year. During the 385 hours of total runtime, the gasoline engine was required to run less than half of the time.

Inside Nissan's Hybrid Transmission
An adaption of Nissan's corporate seven-speed autobox is at the heart of the M Hybrid. In place of the usual torque converter, a computer-controlled dry clutch pack is integrated into the transmission case between the engine and gearset. This is the primary clutch pack, and its purpose is to engage the engine when needed for propulsion or to charge the battery pack. If you're clever, you'll realize that this wording means there's a secondary clutch pack elsewhere. There is, and we'll get to that.

The single electric motor is sandwiched between the primary clutch pack and the transmission's gear cluster. It's powered by a 1.3 kW-hr lithium-ion battery pack supplied by AESC, the same battery manufacturer that furnishes the Nissan Leaf electric vehicle. The battery pack is housed between the M Hybrid's trunk and backseat.

At the output end of the transmission, aft of the gear cluster, is the secondary clutch pack. This wet clutch is smaller than the primary clutch pack and its purpose is simply to disconnect the powertrain entirely from the driveshaft when required.

Imagine the M Hybrid is waiting for a red light to change. In this situation, the vehicle is running, but stationary. If the electronic overlords decide that the battery needs to be charged, the system opens the secondary clutch, engages the primary clutch and turns the engine on. Were it not for the smaller secondary clutch pack decoupling this fornication from the driven rear wheels, the car would promptly propel itself into the intersection.

Driving the Prototype M Hybrid
We took a brief drive in an early prototype of the Infiniti M Hybrid at Nissan's Grandrive proving ground south of Tokyo. In Nissan's parlance, it was a PT1 car, meaning it was a somewhat early prototype. Still, the drive gave us an idea of what the final production version will be like.

In two words, it will be powerful and familiar. Nissan's V6 has always had plenty of grunt, and when you combine it with a torque-rich electric motor, the M Hybrid gets up to speed in a hurry. And unlike CVT-equipped hybrids, the discrete shifts from the seven-speed gearbox make for a very natural driving experience as the revs climb with vehicle speed. If you've ever been irked by the seemingly arbitrary rubber band-ness of CVT-equipped hybrids, you'll love the M Hybrid.

Electric-only operation is smooth and silent and the sensation of extra vehicle mass, while noticeable, does not dominate the M Hybrid's feel on the road. Its steering is less artificial-feeling than the full-electric power steering found on some hybrids. Of note is that Nissan's system is electrohydraulic, meaning it's got an electrically driven hydraulic pump that only provides assist when needed and shuts off the pump when it's not.

Since the brakes are juggling the duties of regeneration and stopping, the pedal response is somewhat synthetic-feeling. Calibration work pertaining to the powertrain, steering and braking systems was still under way at the time of our drive so Nissan still has time to iron out the glitches.

One-Upping the Competition
Nissan's strategy of using two clutch packs and one electric motor, says the company, is more efficient and less costly than systems that instead employ a CVT and two electric motors. Systems, say, like the one used by Lexus in the GS 450h. That car, it turns out, serves as both the M Hybrid's benchmark for smoothness and its primary competition.

On paper, the M Hybrid handily one-ups the GS 450h — the Infiniti's got 369 combined horsepower to the Lexus' 340 and is expected to turn in better fuel economy, particularly on the freeway.

It's far too early to know particulars like EPA fuel economy numbers, but Nissan's big brains expect the M Hybrid to virtually replicate the numbers of an autobox-equipped 1.8-liter Versa, which returns 24 and 32 mpg, respectively. The GS 450h's fuel economy is 22 city/25 highway mpg.

The Underbelly of Hybrid Economy
The trade-offs for the M Hybrid's hybrid-ness, as is typical when it comes to such vehicles, are price and weight. The M Hybrid weighs about 4,125 pounds, some 265 pounds more than an M37, and loses some 20 percent of its trunk volume to the hybrid battery pack.

Pricing isn't yet nailed down. However, Infiniti brass reckon that the M Hybrid will ring in at a hair less than $54,000 when it goes on sale next spring, which is at the high end of the range between the entry-level M37 and the range-topping V8-powered M56. This means that the M Hybrid won't be cheap, but ought to undercut the Lexus.

When you factor in the M Hybrid's significantly higher fuel economy and the promise that the M's inherently superior driving dynamics will be retained, the Lexus GS 450h is in danger of becoming wholly overshadowed. How's that for gratitude?

Edmunds attended a manufacturer-sponsored press event to facilitate this report, which originally appeared on insideline.com.