“Something wicked, this way comes.”That was the first thought to enter my mind upon seeing the new Infiniti M35 Hybrid.The Infiniti’s menacing outward appearance should be the first indicator that this is not your typical fuel-efficient sedan. In fact, it is only appropriate that Halloween is just around the corner, as theMHybrid I drove was something of a luxury sedan hobgoblin, with“Black Obsidian”skin, and“green,”hybrid innards.

This hybrid’s drivetrain is also fitting for the mischievous time of year, as it is something of a Frankenstein’s Monster: a tool conceived for good, fuel-sipping intentions, but used, in practice, for powerful, aggressive acceleration.

Season-appropriate allusions aside, some old-fashioned notions about cars need to be put to bed. Notions about diesel cars being dirty, or about Kia still producing budget econo-boxes are simply false. The same can be said for the un-fun hybrid. Sure, cars like the Prius tune the hybrid drivetrain for optimal fuel efficiency, but the luxury ranks are employing the same gas-electric formula with improved acceleration in mind, allowing for the power of a V8, but without the same hit on the gas tank.

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And with the look of the M, who needs the bite of theV8.The billowing grille, sinewy headlights, and haunch-like fenders look plain mean.The flowing lines of the body are arguably the most attractive in the premium sedan market, certainly among the Japanese players. While the conventionally powered versions of the M possess larger 20- inch wheels, theMHybrid features practical 18-inch wheels, as they are the ideal size for fuel-efficient driving. Excessively large wheels hinder fuel economy performance, and the size of theMHybrid’s wheels displays a clear compromise between fuel economy and vanity.

Compromise is not necessary in the cabin of theMHybrid, where asymmetrical stitching in the seatbacks makes for a defining interior feature for this premium sedan. Our test model provided heated and cooled leather seats, a Bose stereo system with speakers in the shoulders of the front seats, and a comprehensive navigation system with live traffic and weather updates.

The combination of lane departure warning system and distancesensitive cruise control were extremely helpful in navigating traffic. The latter uses a sensor in the lower front grille that monitors traffic ahead of you. Simply set the speed and the distance, and if you are cruising along at 65 mph and someone pulls into your lane at 60 mph, the M will slow to match that 60 at a safe distance.When the car pulls out of your way, the M automatically accelerates back to the pre-set 65 mph.

Acceleration in theMHybrid is effectively brisk. In the center console, the Infiniti Drive Mode Selector lets you select a variety of modes: Snow, Eco, Normal, and Sport. Eco and Normal allow for comfortable driving, achieving the max 27-mpg city, and 32-mpg highway.

Switching the selector into Sport brings the combined 3.5-liter V6 and 50 kilowatt electric motor to life. The motor receives power from an advanced lithium-ion battery pack, which also employs regenerative braking. The net output of this system is 360 horsepower and 258 pound feet of torque. Power is sent to the rear wheels through a 7-speed automatic transmission, and makes the 0-60 sprint in under 6 seconds. While the M56 Infiniti V8 does it in 4.8 seconds, it gets only 16 mpg city, and 24 highway—not even close to the 29.9 mpg that we observed in mixed driving conditions for the hybrid.

Leave the M Hybrid in sport mode and you’ll forget the V8 version of the M exists. While cars like the Prius use the hybrid system for modest acceleration, automotive engineers are finding that an electric motor and gas engine can work together to provide a truly exciting driving experience. Even with the battery pack, the M35h still weighs less than the all-wheel drive M56, and it shows when diving into a corner. Driving enthusiasts can have some real fun reaching the apex of onramps and off-ramps, while that moment of braking right before the turn helps build up electric power through the use of regenerative braking.

The M35h features hybrid-electric power steering.While many automakers have gone to full electric power steering, theMHybrid combines electric assist with a more traditional hydraulic assist. The result is a more connected driving feel that avoids the disconnect of a full-electric system.

So what is this all-encompassing marriage of performance and fuel efficiency going to cost? The 2012 M35h comes with a base MSRP of $54,200, less than the $60K price tag of theV8-powered M56.Things get tricky in the options, though, as choosing the M35h requires selecting the $4,200 Premium Package, and the $3,900 Deluxe Touring Package. The Technology Package, which featured the blind spot warning system and intelligent cruise control costs $3,050. All told, a fully loaded M35h will cost upwards of $66,000.

But if you can get used to the horror of writing a $900+ check every month for a 36-month lease, the M35h is one impressive machine. Such performance out of a hybrid is a sign of things to come, and a portent of the future of fuel-efficient driving.Through a devilishly attractive appearance and a form of gas-electric sorcery, theMHybrid is a perfect luxury sedan for the season, and an amazing hybrid for all seasons.