We're doing final drives of new and updated vehicles from the 2015 model year, and one we've been keen on revisiting is the Infiniti Q50.

Our first drives were in pre-production cars, and with glitches in its dual-screen InTouch infotainment system and with its troublesome Direct Adaptive Steering steer-by-wire system, the Q50s we'd experienced felt as if they weren't ready for prime time.

"I want to love the Q50, but..." was how the chats kicked off, actually.

A shame, because the Q50's lovely shape and interior work so well on the foundation of the old G37, especially its excellent suspension tuning. With dual-flow rear shocks and a lot of sound deadening grafted on in the transition to a new generation, the Q50 was clearly ready to became an even better performer.

Fast-forward to this winter, when the car gods dropped a Q50S 3.7 with RAYS 19-inch wheels and summer tires into our garage. If you're wondering how we'd spec a Q50, this is it. It's the version that can roll with the best sport sedans of its size.

Better steering helps

A few things curry favor in this particular Q50. First, it sticks with the hydraulic steering that was a highlight of the G37 (now called the Q40). That alone, plus the summer treads, gives the Q50 S actual steering feedback, the kind you don't feel much anymore in any of the mid-size luxury sedans in its size class--even the vaunted BMW 3-Series, even our current crush, the Cadillac ATS. It's not at all wandery or vague, which some of us had felt in those early drives--which reconfirms our sentiment that, if you're shopping a base version of any of these sport sedans, you're getting a watered-down tune that doesn't ring as true to any of these brands. That, and you're probably leasing one. We much prefer the Q50 S, with hydraulic steering, sport suspension, and summer tires, thanks very much.

Critically, our car skipped the Direct Adaptive Steering system. The drive-by-wire experiment left us cold in initial drives, with awkward response and feedback. Infiniti's been improving the system, but we haven't been in one with the latest state of tune just yet. It's on the docket.

For power, the Q50 is competitive without adding on turbochargers you'll find in its rivals. In this tune, the Q50's 3.7-liter V-6 represents the best-ever state of noise and vibration control in Nissan's VQ engine family, but it's also probably the end of the line, in terms of development. New sixes are coming--but this one's delightful, with 328 horsepower and 269 pound-feet of torque. It's less coarse than it was in the G37, though it revs more freely and mates better with the throttle-blipping seven-speed automatic. Missing from the equation: any manual transmission.

Styling ups, infotainment downs

Where the Q50 really distinguishes itself is in its suave lines and plus-size space. The new sheetmetal is simply striking. It combines the sensuality of the bigger Q70 in exotic new ways, especially at the exaggerated intersection of curves and surfaces behind its rear doors. The interior's style is money compared to any BMW 3-Series; it looks much richer and modern, even without some of the more expensive trim packages.

Inside, the driving position is nice and low, and the front seats have some of the high-density structure Nissan fitted to its Altima. They're are superb for long-distance comfort.  Rear seat room is far better than the Cadillac ATS, the new C-Class, just about on par with the 3-Series. Yes, the wide center stack chews up some room, but it feels intimate--and intimate, not claustrophobic, is how a sport sedan should feel.

The infotainment system in the Q50 remains a skipped beat. Twin screens sounds like a great way to skirt the intersection of connectivity and ergonomics, but the Q50's system still feels a little overbaked. All the control happens on the lower screen, while the larger one is hands-off, display-only. Systems like Volvo's Sensus setup, which combines infrared and capacitive touch in a beautifully obvious interface, seem to be the way forward here.

In terms of value, the Q50 is a clear winner. For $47,755, our Q50 S 3.7 test vehicle came outfitted with navigation, sport suspension and tuning, a sunroof, a rearview camera, 14-speaker Bose sound, aluminum trim, and the $1,800 performance-tire package (245/40R-19 front and 265/35R-19 rears). Safety tech like blind-spot monitors and forward-collision warnings were available in a $3,200 package, though, and to get Infiniti's excellent surround-view cameras, you must spend another $3,100 and must take the Direct Adaptive Steering in the bargain. We'd prefer standard collision avoidance and a stand-alone surround-view option.

As it is, crash-test ratings in the Q50 are improved somewhat over those of the G37, and the new model is an IIHS Top Safety Pick+.

Head tohead

Call out its rivals, and the Q50 adds luster. Outfit a similar rear-drive, V-6-powered ATS and you'll come in a couple grand higher and get standard forward-collision warnings. You'll also get a hefty discount based on slow sales--something we find hard to believe, but it is what it is. The ATS is a top safety scorer, too. It remains our favorite in this niche by a slim margin and despite a very tight back seat and trunk, because of its signature look, stellar handling, and excellent safety ratings.

Spec out a similar BMW 335i with Premium, Driver Assist, and Technology packages (which include a few extra features like a head-up display and parking sensors), and the $51,550 price tag looms larger than the Q50's. The 3-Series also has issue with the IIHS's new small-overlap test, where it scored "marginal." A rearview camera remains an option, too. The Infiniti is a better value, with arguably better styling and comparable handling. In a bit of a surprise, the Q50 now ranks ahead of the 3-Series in our numeric ratings.

The Q50's closest rival, in terms of looks and size, just might be the new Mercedes C-Class, a car with captivating styling and sport-sedan credentials burnished with a new C63 AMG variant. With a rearview camera and sport air suspension, it checks in just below $50,000--and with crash-test scores still in the offing, it's likely to be tied with the ATS as our top-ranked car in this class as soon as the NHTSA publishes some data. For now, it's ranked alongside the Q50.

Though the badge doesn't have the allure of any of those competitors, the Q50 has matured into a solid rival. It's also amassed a reputation for durability that stands out. Infiniti laid out a more ambitious agenda than ever before for the Q50--and despite some teething problems at launch, it seems to be succeeding.

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