Infiniti's M sedan has finally come into its own with the current generation. Previous versions drove pretty well and had decent interiors, but were invisible on the street and in the marketplace. The current, curvaceous design is a head-turning standout. And Infiniti's interior designers have upped their game, creating a sumptuous new cabin. The car's chassis -- provided one sidesteps a few overly intrusive electronic aids -- has all the smoothness and poise a premium car should.
Beyond all that, the other big change with the new M is the addition of a hybrid model. Situated in between the expected six-cylinder (M37) and V-8 (M56) versions, the hybrid claims to marry the power of an eight-cylinder with the fuel economy of a four-banger. That's a pretty big boast, but it's not necessarily trash talk.
Mechanically, Infiniti's hybrid system is a little different than most. The electric motor is sandwiched between the 3.7-liter V-6 engine and the transmission. Infiniti uses a conventional seven-speed automatic rather than a CVT -- less efficient maybe, but vastly more enjoyable to drive. The location of the motor allows the engine to shut down when you lift off the gas, even at highway speeds. A lithium-ion battery pack is recharged via brake energy regeneration.
The V-6 and the electric motor combine to produce 360 hp, which outmuscles the M37's V-6 (333 hp) but doesn't equal the M56's V-8 (420 hp). However, the hybrid has the advantage of the electric motor's 199 pound-feet of torque, which is available at a low 1770 rpm. Thus, the M hybrid lunges off the line, chirping its tires as the traction control system struggles to keep pace. It also rockets ahead during passing maneuvers. The car feels almost as frantic as the V-8, and definitely quicker than the V-6.
Even so, it's EPA rated at 27 mpg city, 32 on the highway. Its most direct competitor, the Lexus GS450h, is about to be replaced and maybe doesn't make for a very fair comparison, but that fact that the Lexus hybrid gets a comparably pathetic 22/25 mpg just shows how quickly hybrid technology is advancing. Unfortunately, I was only able to achieve an indicated 25 mpg in my week with the car, but that was almost all in-town driving, and with our steep hills here, it's not uncommon for cars to do worse than their EPA city estimates in my hands.
I might have done better had I engaged the Infiniti's "eco pedal," which is available in all versions of the M sedan, and is accessed via a drive mode selector dial. But this technology, wherein the gas pedal pushes back at you if the car decides you're driving too aggressively, is almost as annoying as having a hyperventilating mother-in-law smacking you with her purse whenever she thinks you're driving too fast. Better to leave the dial in normal mode, even at the loss of a few MPGs.
Even without a mother-in-law riding shotgun, the M hybrid does pack on an additional 276 pounds compared to the M37. But, at 4129 pounds, the total is still about the same as a non-hybrid BMW 535i. And the other good news is that much of the additional weight is due to the battery pack, whose location behind the rear seat at least puts the additional burden on the rear wheels, rather than the front. The hybrid version of the M sedan remains a very sweet-handling luxury car. In fact, I preferred it to the M56 that I drove, which was equipped with the sport package. That option (not offered here) includes rear-wheel steering, which makes for less predictable cornering response, as it gives you what feels like a second yaw moment after you turn the wheel. And speaking of steering, even though the M hybrid uses electric power steering instead of the hydraulic set-up in its siblings, the steering feel and linearity is undiminished, as this electric system is incredibly natural feeling.
So, what are the downsides? There are a few. Like most hybrids, the Infiniti suffers some non-linearity in its brake pedal modulation and in its throttle tip-in. Additionally, once or twice the system got momentarily tripped up, with delayed action and then an abrupt downshift. Overall, though, the issues aren't severe enough to spoil the driving experience.
Other negatives include a sacrifice of 4 cubic feet of trunk space to the battery pack, and the rear seatbacks no longer fold down. Also, there's no all-wheel-drive option, as there is with the V-6 and the V-8 cars.
Assuming you can live with rear-wheel drive, the M hybrid makes an awfully strong case. Compared to the M37, the hybrid costs $5000 more, but it trounces the M37 in fuel economy, besting it by 9 mpg in the city and 6 mpg on the highway. Driving an average of 15,000 miles annually, you save nearly $800 per year (with gas at $3.95/gallon) with the hybrid. So the payoff time is just over six years -- less if you factor in the hybrid's expected higher resale value. Oh, and the hybrid is way faster.
It's against the M56, however, that the hybrid looks even better. It drives with very near the alacrity of its V-8 sibling, but it's $5400 cheaper (although the M56 has more standard equipment). Additionally, the hybrid saves more than $1000 per year in fuel costs.
I'd love to see Infiniti engineers perfect the hybrid driving experience because, even as it is, the M hybrid seems very much like the high-performance sedan of the future.