Brand-spanking new for 2012 is the M35h, a hybrid gasoline-electric variant. As expected from its badging, the new frugal sibling is fitted with a slightly smaller 3.5-litre V6 (it's the VQ35HR, also found under the hood of the previous-generation M35). The all-aluminum four-valve powerplant is rated at 302 horsepower and 258 pound-feet of torque. Bolted to the back of the engine is a seven-speed electronically controlled automatic transmission, identical in type and ratio to the gearbox in today's torque-laden eight-cylinder M56. Sandwiched between the engine and transmission is a 50 kW electric motor with a power rating of 67 horsepower and 199 pound-feet of torque (it is a one-motor, two-clutch parallel hybrid system).

According to Infiniti, the engine/motor package develops a combined 380 horsepower (Infiniti isn't releasing torque figures, but combined we figure they are making an easy 400-plus pound-feet).

While there's plenty to like about the barely-touched exterior and wonderfully-appointed cabin, the real surprise comes on the road. The M35h drives just like we want it to ? fast and frugal. Infiniti's parents at Nissan consistently do powertrains right, and its first in-house hybrid is no exception.

The strong VQ engine and traditional geared seven-speed transmission make a great pair, delivering strong off-the-line power with a kick of boost from the electric motor. The electronically controlled gearbox allows the distinctive-sounding V6 to spin up the tachometer a bit before grabbing the next ratio. Press the accelerator with authority, and the abundant torque launches the sedan off the line with gusto. Infiniti isn't releasing numbers (it never does), but we bet that the rumors of a sprint to 60 mph (96 km/h) in just 5.5 seconds are not only true... but possibly conservative.

The steering (a custom electric system for the hybrid) and brakes (identical to the gasoline-only models, with the exception of a regenerative braking system that turns kinetic energy back into electricity) work well, and exactly as advertised. The non-sport suspension (only modified for the higher curb weight) gives the M35h surprising sure-footed agility. Thanks to the batteries hidden behind the second row of passengers, the weight distribution of the hybrid is actually better than that of its siblings. Infiniti quotes 51/49 (percentage front/rear) for the M35h, compared to 54/46 for the M37 RWD (the M56 RWD is 56/44).

Completely out of sight, but taking more than their share of trunk space, the bank of high-output lithium-ion batteries offers 50 kW of output at a nominal 346 volts ? enough power to propel the Infiniti sedan to 62 miles per hour (100 km/h) on electric power alone.

When the driver's aggression is under control, the M35h shows its softer, environmentally conscience side. As expected, the M35h is equipped with auto start/stop to save fuel when the vehicle isn't in motion (the only Infiniti configured with the fuel saving technology, as of today). Even better, at lower speeds the combustion engine shuts down placing all propulsion duties firmly in the hands of the electric motor. With the exception of a slight hum from the all-season tires, things get eerily silent. Infiniti doesn't want owners to run over hapless pedestrians around town, so they've equipped the M35h with a strange electronic noise that is emitted at low speeds.

Compared to its closest rival, the Lexus GS 450h, the M35h provides comparable acceleration but without the numbing (and boring) continuously variable transmission power delivery. The stepped gearbox simply makes the M feel sportier in nearly every driving situation ? it's genuinely fun and engaging to drive. Finally, and most important to everyone in the green segment, the Infiniti absolutely slaughters the Lexus when it comes to fuel economy.

Official EPA fuel economy figures for the 2012 Infiniti M35h come in at 27 mpg (8.7 l/100 km) city and 32 mpg (7.4 l/100 km) highway, or 29 mpg (8.1 l/100 km) combined. (During a full day of aggressive media test drives around Hollywood and Santa Monica, our test car averaged an impressive 25.3 mpg (9.3 l/100 km) with 47.2 per cent of our driving in pure electric-only mode). According to the EPA, the 2011 Lexus GS 450h will earn 22 mpg (10.7 l/100 km) city and 25 mpg (9.4 l/100 km) highway, or 23 mpg (10.2 l/100 km) combined ? blame its six-year-old technology for those embarrassing numbers.

The all-new "have your cake and eat it too" M35h hybrid isn't flawless, but it is one of the best arguments we can come up with to convince a passionate driver to sit behind the wheel of a green-themed vehicle. For the record books, the 2012 Infiniti M35h just may be the first hybrid carrot worthy of capturing the appetite of an enthusiast. Infiniti has a winner on its hands ? and it could be the best M in the automaker's lineup.