The days of half-hearted mid-life updates in America's midsize sedan wars are over. Following recent substantial refreshes to segment kingpins like the Toyota Camry and Honda Accord , Nissan's 2016 Altima is arriving with its own healthy dose of upgrades. The automaker is calling the change one of its most extensive mid-cycle alterations in its history, with styling revisions inside and out, fuel economy improvements, chassis tweaks and the addition of a sportier SR model. With the Altima being Nissan's perennial best-selling model, the stakes to stay relevant could hardly be higher.

Nissan's eye-catching "Energetic Flow" design language (already on display on its Murano crossover and Maxima sedan) has been grafted onto the Altima with good results -- everything from the A-pillar forward is new, including a V-Motion grille, boomerang headlights, fenders, bumper and hood. Out back, the light housings, bumpers and trunk lid are redesigned, as are the model's wheel designs. Combined, these changes help give this family sedan some much-needed visual punch compared to its drab predecessor, a design that was comfortably at home in rental fleets.

Another upshot to the Altima's sleeker appearance is that it's also slipperier through the air. Credit goes to those redesigned fascias, additional underbody covers and active grille shutters (on four-cylinder models), all of which help improve the Altima's coefficient of drag from 0.29 to 0.26. Interestingly, the latter figure now matches that of Nissan's GT-R supercar. (File that nugget away in case you find yourself trying to one-up the other parents at your kid's soccer game.)

Sleeker looks come courtesy of a new front end featuring a V-Motion grille like its costlier siblings.

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Those aerodynamic improvements work in tandem with upgrades to the Altima's 2.5-liter four-cylinder to nudge its EPA-rated highway fuel economy upward from 38 to 39 mpg. Yet despite the presence of a revised compression ratio, decreased internal friction measures and a revamped oil pump, the engine's 182 horsepower and 180 pound-feet of torque remain unchanged. Regardless, the SR model I sampled provided class-competitive performance around town in stop-and-go traffic, along with enough grunt for expressway merging. Those looking for even more power can still splurge for the 3.5-liter six-cylinder with 270 hp and 251 pound-feet.

A continuously variable transmission remains standard with either engine, and for 2016, it's been upgraded with Nissan's third-generation D-step shift logic. This new programming provides more responsive performance and a traditional acceleration feel thanks to simulated gear shifts, even under wide-open throttle. The payoff? The obnoxious constant droning sound that usually accompanies continuously variable transmissions is no more.

The D-step shift logic also surprises with how quickly it executes simulated gear changes. Remarkably, the action seems on par with some dual-clutch transmissions I've experienced. Response to paddle-shift commands is particularly impressive, adding to this sedan's fun factor. When left in fully automatic mode, the Altima's transmission does a fine job masking the fact that it's a continuously variable unit, and it actually manages to feel very much like a traditional torque-converter automatic in nearly every circumstance.

Chassis modifications aimed at giving the Altima a sharper drive character include new shocks, rear springs, bushings, tires and retuned electronic hydraulic power steering. Nissan claims the alterations result in more tied-down handling and improved steering feedback without sacrificing ride comfort. The SR takes things a step further with firmer dampers, springs, thicker antiroll bars and more aggressive 18-inch Dunlop SP Sport 7000 all-season tires.

Inside, there's a revised center stack and console with a 5-inch color display standard and 7-inch screen available on vehicles with navigation. The cabin also features upgraded soft-touch materials, additional sound deadening and an acoustically laminated windshield, delivering a pleasingly refined experience. Finding a comfortable seating position is easy, infotainment controls are intuitive, major interior touch points feel high quality and isolation from road and wind noise once underway is very good. The SR's interior differs from other Altima models only in that it features blue accent stitching on the seats, steering wheel and shift knob -- Nissan could have done more to dress up this sportiest Altima and make it feel special.

Telematics features offered under the NissanConnect umbrella include automatic collision notification, smartphone remote start, stolen vehicle locator and dealer service scheduling. If you have an iPhone you can use Siri Eyes Free voice recognition, but Apple CarPlay and Android Auto remain conspicuously absent from the Altima's options list.

A 5-inch color display is standard on the Altima, while a 7-inch unit is available on models equipped with navigation.

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Newly available safety technologies include predictive forward collision warning with emergency auto-braking, intelligent cruise control and rear cross-traffic alert. I didn't have the chance to fully test these new capabilities during my test drive, so properly assessing them will have to wait until our full review.

The addition of the SR model seen here is the result of rivals Toyota and Honda doing quite well with their sportier midsize sedan offshoots. According to Nissan's internal research, Toyota's Camry SE accounts for 40 percent of its sales. With the Altima SR, Nissan hopes to get in on the action, attracting different buyers with its sharper looks and performance. On top of the aforementioned suspension changes, paddle shifters and interior accent stitching, the SR also receives smoked headlight housings, fog lights, a decklid spoiler and exclusive 18-inch aluminum wheels. SR models can be had with both four- and six-cylinder engines.

A Michigan late-fall morning spent testing a 2.5-liter Altima SR let me experience this more athletic midsize sedan firsthand, with additional heft in its steering noticeable from the first turn of the wheel. Through the bends, the SR was quicker to respond to steering inputs, with crisper turn in, and the chassis offered decent grip paired with improved body control and less roll. Previously, the Altima's steering felt disconnected and somewhat sloppy, so this performance was a substantial improvement. Of course, it's hard to argue that the 2015 model's cushy ride was great for absorbing the bumps and potholes of less-than-stellar road surfaces, but the updated Altima still offers a compliant ride, even in SR trim.

The 2016 Nissan Altima is just now reaching dealers, with prices starting at $22,500. The SR begins at $24,470 with four-cylinder power, or $27,390 in V6 spec, with all MSRPs excluding a $825 destination charge. Pricing for Australia is not yet available, but the model should start around AU$33,500. UK Nissan fans will continue to make do without the Altima.

Overall, the Altima SR does a fine job of delivering a higher-performance family sedan experience, and its more aggressive styling should woo consumers cross-shopping the Camry SE and Accord Sport. Like its best-selling rivals, however, the SR is still by no means a full-fledged sports sedan. Instead, think of it as a lite midsize sports four-door. In the end, buyers seeking the most athletic midsizers on the market will still want to check out the Mazda6 and Kia Optima .