That youthful, playful and slightly rough around the edges Subaru we once knew has passed through its awkward puberty stage to become a fully grown up automaker. No longer cranking out the outlandish, like the Brat or Baja, Subaru has chosen to focus on the mainstream with its redesigned Legacy.

Yet, as our week-long evaluation told us, that doesn't mean that Subaru has become dull with age.

What is it?

Unless you're within about 100 miles of Boulder, Boston or Portland, you could be forgiven for not knowing that this Legacy is actually the fifth generation variant of a nameplate that dates back to 1989.

This latest Legacy sedan represents a comprehensive rethinking of the line - and it was recreated with the lucrative North American market's needs in mind. That latter statement is usually a sign that all the engineering emphasis was put into making the seats wider, the cupholders bigger and the suspension softer, but as we discovered, that's just not the case with the Legacy.

Our tester was equipped in a new-for-2010 trim level that probably won't account for a big slice of Legacy sales. Featuring Subaru's biggest six-cylinder boxer engine but an otherwise base trim level, our test car listed for a reasonable $25,690 including destination. Subaru also offers the 2.5i, a 170-horsepower, naturally-aspirated four-cylinder boxer, as well as a more enthusiast-oriented, 265-pony, turbocharged 2.5GT. All three engines are offered in a dizzying array of trim levels, so rest assured that there's a Legacy suited for your lifestyle out there.

The Indiana-built Legacy sedan is a kissing cousin to the hot-selling, ruggedized wagon Outback.

What's it up against?

The Legacy competes against some of the best - and best-selling - in the business, but it's hard to categorize this left-of-mainstream sedan. Subaru hopes it will bite off a chunk of Toyota Camry and Honda Accord sales, but for many buyers, the mostly unfounded fears of all-wheel-drive maintenance and fuel efficiency will be a turn-off.

With the added dose of sport ingrained into modern Subarus - these cars are brought to you by the guys who have long dominated every type of rally driving available - the Legacy also goes up against more enthusiast-oriented mainstream sedans like the Mazda Mazda6 and Nissan Altima.

Then there's the all-wheel-drive element, meaning the Legacy does battle with the four-wheeler versions of the Ford Fusion and Mercury Milan.

To muddy the waters even more, higher-trim Legacys start to feel downright entry-luxury in their inner trappings, meaning the Saab 9-3 and Audi A4 might be on would-be Legacy buyers' radar.

Any breakthroughs?

Subaru brought to the table more of what we love: More displacement, more power, more miles per gallon, all the while using 87 instead of 91 octane. These engineers are to be applauded.

The all-wheel-drive system has been enhanced; 3.6R models feature a planetary center differential and limited slip rear differential capable of transitioning power to any wheel that needs it.

How does it look?

Power and traction are longstanding Subaru virtues - style is not. For the new year, the modestly enlarged Legacy - which grows mostly in height, width and wheelbase - eschews its predecessor's conservatively tasteful and upscale look for a more outlandish style that doesn't sit well in our stomaches.

Most notable - and notorious - are the flared fenders, an increasingly common design theme in the auto industry. They're at odds with the Lexus GS-esque tail and the swept-back, fisheye headlamp clusters, both of which would be acceptable on their own but seem misplaced when slapped together. It looked to us as though competing design languages drove the Legacy's new look.

Although not a bad-looking car per se, the Legacy's design lacks the mature, cohesive style that emerges from Europe or North America. It typifies the age-old stigma of Japanese design in ways the outgoing Legacy avoided. The basic shape is pleasing, and we even grew to accept the aggressive fender flares during our evaluation. Yet there's room for improvement and we hope that a midcycle refresh will allow Subaru to hone a more well-thought-out style of its own.

And on the inside?

Its low-rung specification notwithstanding, our Legacy sedan's cabin proved an exceedingly comfortable place to spend time. Compared to the outgoing Legacy - which had an upscale-looking, but tight interior, the new body takes a more mainstream design approach and adds considerable space.

Rear seat room has improved from econo-car tight to downright spacious thanks to clever packaging and a longer wheelbase, while the front seat also adds some wiggle room. The front seats, covered in a grippy cloth material, proved comfortable for hours at a time despite lacking adjustable lumbar support.

The dashboard is higher up and features more storage places, addressing one of our issues with the outgoing interior. Its overall design, shared with the Outback, is functional and materials selection is acceptable for the class. In our base 3.6R test car's trim, the materials were class competitive and the assembly quality was top notch.

The deep trunk will have no problem swallowing luggage, but the lid - supported by gas struts, not hinges - doesn't open very far. We whacked our foreheads on it more than once during our evaluation.

We were a little disappointed with the level of equipment included at the 3.6R's trim level - a power driver's seat, leather covering the steering wheel and gearbox knob, and RDS functionality for the radio would go a long way towards improving creature comforts by adding just a few bucks to the bottom line. Traditionally, Subaru has offered a cut-rate Special Edition package for the Legacy and we hope these features will be added soon. At least there are some pleasant surprises inside that help set the Legacy apart, like berber-style floor mats, uniquely grained faux-metal trim and a nifty economy gauge to help drivers use less gasoline.

But does it go?

It might seem odd that Subaru offers two high-performance engines with similar power outputs - the 3.6-liter flat six in our tester is down just nine horsepower compared to the turbo 2.5GT. Yet the cars have an entirely different mission - the 2.5GT is aimed at enthusiasts who will cope with a little lag in exchange for the rush of a turbo, while the 3.6R is aimed at more mainstream users seeking smooth, consistent power delivery - which it delivers in spades.

From any speed, the 3.6R is positively fast, especially at speed, when its ample mid-range torque comes into play. Though rated at a fairly conservative 247 lb-ft. of torque at 4,400 rpm, this 3.6R strikes us as the understatement of the year - we can't think of another naturally-aspirated six-cylinder that delivers this kind of grunt across the rev range (we did pop the hood to see if Subaru had snuck a turbocharger in there). If anything, we think the 3.6R has been tuned too much for performance at low speeds, where a jumpy throttle proved tough to modulate. An owner would get used to it after a few weeks of driving, but would-be passengers might want to brace themselves for the interim.

Despite its power, the Legacy didn't guzzle 87 octane fuel; its 18 mpg city and 25 mpg highway EPA ratings are par for the class and seemed accurate in our driving. We averaged 21 mpg in driving that tended towards the aggressive.

The 3.6R is silky smooth at idle and makes only a distant growl at speed, unlike the comparatively gruff four-banger. It's mated exclusively to a five-speed automatic with rev-matching paddle shifters. Generally, the transmission did not struggle to find a gear and was happy to fire off rapid downshifts when called upon. We played with the paddles for a bit and found that, while they are happy to induce those rev-matching downshifts, moving up the gears seemed a little laggy. We suspect almost every owner will keep the transmission in D for most of their driving.

Rarely do we seek a week of rain showers when we evaluate a press vehicle, but that's just what we wanted for the all-wheel-drive Legacy. Though the neighbors might not have appreciated our front yard rain dance, it obviously paid off: A downright deluge from the clouds had us gathering wood for an ark until we hopped in the Legacy.

Man, does this thing have grip. Even at high speed in standing water, the Legacy refused to let go of the tarmac. Its steering spoke to us in ways we've never before felt in a family sedan, reminding us that all four wheels had things under control. When the rain finally stopped, the Legacy was a delight on dry, curvy roads, too. A balanced chassis lent to its neutral, pushable feel as it begged to be thrown hard into corners.

Flat cornering typically results in a choppy ride, but that wasn't the case with the well-dampened Legacy. Although the ride tends towards firmness, it remained controlled and refined even over the roughest roads we could find. Adding to the feeling of sophistication was an especially stiff body.

Why you would buy it:

The Legacy is your car if you're willing to admit that a four-door family hauler need not signal the demise of your days as an enthusiast.

Why you wouldn't:

You're hooked on Camrys or Accords and are afraid to try anything else.

Leftlane's bottom line

The last time we tested a Legacy - about a year ago we sampled a previous-generation 2.5GT - we said, "the Legacy stands as potentially the most underrated automobile on the market today." A year later, we still feel the Legacy is an absolute standout in the family car segment. Yet with Subaru's phenomenal sales - think about it, Subaru's sales are up in a recession! - perhaps no longer is the Legacy truly underrated.

We hope Subaru doesn't rest on its laurels. The Legacy isn't perfect, but for what it is, we can't think of a four-door that tickles the enthusiast soul more than this one. It's not a car you'll stare at as you walk away from it, and it's not one you'll agonize over washing. But it's one that will dutifully serve your needs every day while putting a smile on your face at each curve.

2010 Subaru Legacy 3.6R base price, $24,995. As tested, $25,690.

Destination, $695.

Words and photos by Andrew Ganz.