The confusion is quite understandable, of course. If you haven’t been paying close attention since last year, when rumors surfaced suggesting that the Infiniti G37’s replacement would source its underpinnings from Renault-Nissan partner Mercedes’ parts bin, it would be easy to get the wrong idea about the new Q50.

A stint behind the wheel could also prove misleading. After all, how could something so polished, so refined trace its lineage not to the three-pointed star, but to the entertaining yet rough-around-the edges G37?

The simple answer is that Infiniti’s engineers have managed to achieve the improbable, ironing out the wrinkles from a largely carryover platform while also adding heaping helpings of style and bleeding-edge technology. That isn’t to say that the Q50 manages to steer entirely clear of miscues, though overall, there’s a lot to like about this capable 3-Series rival.

Goodbye G37

The G37 isn’t exactly a bad looking sedan, but the Q50 is simply in a whole different league. To our eyes, it’s muscular yet sleek, stylish but not overwrought, deftly incorporating cues like Infiniti’s double arch grille and crescent-cut C-pillar against a backdrop of sinewy character lines and harmonious proportions.

Underneath, the Q50 features a mildly updated version of the versatile FM architecture that underpins everything from the Nissan 370Z coupe to Infiniti’s G37 sedan and QX70 crossover. The Q50 and G37 share a 112.2-inch wheelbase, while lengthened overhangs mean the Q50 is 0.4-inches longer than its predecessor, which has defied death (along with the badging strategy) and will continue on until 2015 as Infiniti’s entry-luxury offering.

Powertrain offerings include the familiar 3.7-liter VQ-series V6, here making 328 horsepower and 261 lb-ft of torque, and a hybrid system borrowed from the Q70 Hybrid that pairs a 3.5-liter six with an electric motor to produce 360 ponies.

For now, a silky-smooth seven-speed automatic is the only available gearbox. Infiniti tells us that when coupe and convertible variants of the Q50 launch with a manual transmission option in a year or two, there will be enough volume to justify offering a stick shift with the 3.7-liter sedan.

Naturally, rear-wheel-drive is standard, and all-wheel-drive can be spec’d on both models for an extra dose of foul-weather traction. Efficiency ranges from an impressive high of 29/36 mpg city/highway mpg for the RWD hybrid to a low of 19/27 mpg for the AWD gasser.

Looking to try out the best mix of performance and technology, we spent our driving time in the Q50 Hybrid, which combines a standard sport suspension with an industry-first steer-by-wire system and semi-autonomous driving capability.

Road-tested

The hybrid essentially travels incognito, with small badges on the front fenders being the only giveaway to its electrified powertrain. Unlike Lexus hybrids, it doesn’t try to hide its tailpipes behind a spoiler of shame, instead using a pair of prominent, oversized exhaust tips to clearly signal that it possesses sporting intentions.

Step hard on the skinny pedal, and it’s clear that there’s more than enough thrust to back up the look. Acceleration comes in a smooth, linear rush, with the zero-to-60 mph sprint taking a claimed 5.5 seconds. Dynamically speaking, there’s no drop off from the excellent body control and quick reflexes of the G37, but the real news is how a better-dampened ride and more coddling cabin conspire to create a feeling of consummate luxury that was absent before.

Inside, it’s the little details that make a world of difference – the way the wood trim tapers from one side of the console to the other, the gentle, flowing lines of the dual-cowl dash. Tire and wind noise has been reduced to Mercedes levels, and the V6 – a mill generally noted more for power than refinement- announces its presence in the Q50 with only a distant snarl at the upper reaches of the tachometer.

Also worthy of praise is Infiniti’s new InTouch infotainment system. As in the Acura RLX, there’s two touchscreens mounted on the center stack – an eight-inch unit that displays navigation information, and below that a seven-incher that incorporates audio, climate and drive mode controls. Though quite smudge-prone, both feature simple, intuitive menu layouts and, blessedly, very little lag. Further, strategically-placed redundant buttons for frequently-used stereo and climate functions make it easy even for troglodytes to find things in a hurry.

Unfortunately, not all of Infiniti’s technological efforts have been quite so successful. At once an impressive achievement and an answer to a question no one has asked, the hybrid’s standard Direct Adaptive Steering system – a misnomer if we’ve ever seen one – features no direct mechanical connection between the tiller and the front wheels under most circumstances (a conventional system springs into action should the steer-by-wire fail).

Instead, it uses a sensor to measure steering inputs and convert them into front wheel movement, while a force actuator creates artificial feedback. Three different settings are available for both weight and quickness, and it can be adjusted on its own or in concert with Drive Mode select, which also alters throttle response and transmission shift points.

In practice, the system doesn’t seem all that different from a normal electric assist setup with the wheel pointed straight ahead – there’s at least a faint simulacrum of feel – but once the road turns curvy, it starts to fall apart. The slightest turn of the wheel brings with it a totally unnatural sensation akin to cranking a weighted washing machine knob, something that fiddling with the various settings does nothing to help.

On the plus side, it’s accurate enough, and perhaps those who equate isolation with luxury will find it appealing; however, we find it sufficiently off-putting that, were it our money, we’d deem Direct Adaptive Steering reason enough to skip over the Q50 Hybrid in favor of the Q50 3.7 and its standard hydraulic steering system.

Of note, opting for Direct Adaptive Steering is the only way to get a Q50 with Active Lane Control, a camera-based system that reads the painted lines on the road and applies slight steering corrections to keep the sedan from wandering out of its lane. When used in conjunction with Intelligent Cruise Control, which can slow the Q50 all the way to stop and then accelerate back up to the set speed, it provides a degree of autonomous driving capability similar to the new Mercedes-Benz S-Class.

It’s especially useful for traffic jams, although it can also be used to reduce fatigue on fairly straight highways. We found that the system worked essentially flawlessly, with our only gripe being that it tends to correct not by pushing the car back into the center of the lane but by staying right at the edge of the line – a trait that could potentially make the driver or nearby motorists slightly uneasy.

Leftlane’s Bottom Line

By blending the G37’s athleticism with double-take inducing looks and Stuttgartian sophistication, Infiniti has created a fine sport/luxury sedan that should appeal to a broader swath of buyers than its already strong-selling predecessor.

The hybrid model, with its balance of power and efficiency, is arguably the most desirable Q50 in many respects – it’s just a shame about the steering.

Photos by Nat Shirley.