Last September at the Frankfurt Motor Show, we made the claim that the new Euro-spec Mazda6 was bringing sexy back to the midsize sedan market. The version slated for sale in the United States will do the same, but not because it's identical to the one designed for Europe. It's not. These spy shots from Brenda Priddy & Co. show a completely naked prototype that was caught in Detroit. Though at first glance it looks exactly like the 6 that debuted in Frankfurt last year, closer inspection reveals many changes to the car, which corroborates reports we've heard that the U.S. version is also markedly different underneath its skin.

Wow! That looks pretty handsome. I would be interested to see how it stacks up against the usual suspects. I find that the new accord is huge and hideous.

The front seats are too wide to offer serious lateral support, but the 6 feels a full size smaller than it is once you're moving. The Accord and the Camry feel like Buicks by comparison, because the Mazda's body motions are so tight and well-controlled. The 6's steering, administered through a small-diameter, leather-wrapped wheel, is precise in the way none of its competitors' is. Effort builds naturally and progressively off center, and torque steer is admirably absent.

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Without question, though, the four-cylinder Mazda 6 is the handling champ in this segment. The V-6's optional eighteen-inch wheels generate loads of grip, but the lighter engine gives the four-pot 6 balance unlike any other large front-wheel-drive car. At-the-limit handling is nearly neutral, with all four tires generating their share of grip - quite the opposite of the understeer-only Camry, for example.

As this mid-size class matures along with its customers—Mazda looks hopefully toward the 50-to-54-year-olds now—the machinery drifts inevitably toward practiced competence instead of passion, appliances for the road. The Camry has been there for years. The latest Accord comes close. The Altima, alone, still fits in sports clothes. Now comes a new Mazda 6 promising the most difficult of all straddles—refined manners and appointments overlaid on high-spirited reflexes.

After a few hours of driving early preproduction samples around Southern California, we think mission accomplished. Steering is light and alive, yet it grooves in on straight-ahead when the path calls for it. Slack has been zeroed out of brake-pedal motion. Ride is well controlled without being harsh, and noises, both road and wind, are dialed way back. Bottom line: The Mazda 6 was never like this. Think Mazda 7.

Mazda was brave enough to bring the competitive targets (Honda Accord, Nissan Altima, and Toyota Camry) to the launch so we could test drive them back-to-back against the all-new Mazda6. Our seat-of-the-pants impression was that the all-new Mazda6 was undeniably the most enjoyable of the bunch to drive -- as Mazda and their Zoom-Zoom infusion had boasted. While none would be considered a stoplight racer, the 3.7-liter under the Mazda's hood felt a bit out-gunned by Nissan's 3.5-liter VQ (itself rated at 270 hp), even though it wasn't as smooth. The Toyota and Honda felt about as quick as the rest of the pack. A penalty at the pump, not matched with any apparent acceleration advantage, doesn't keep consumers happy in this segment.

Mazda engineers spent a considerable amount of time refining the chassis of the new Mazda6 to make it a more rigid platform. It's all in the name of allowing the suspension to do its work, and improving occupant safety. Independently sprung on all four corners, the newest Mazda wears double-wishbones up front and an E-type multi-link in the rear. Stabilizer bars on both ends keep everything on an even keel. Driving the Mazda6 on some of Southern California's most challenging roads (Mulholland Drive, Stunt Road, and Decker Canyon), the sedan wasn't traumatized like the Camry (think marshmallow soft), or the Accord (what happened to the fun-to-drive Accord?). Diving into corners resulted in expected understeer, but without the feeling that the front tires were peeling off the rims (did we mention how soft the Camry was?). The Mazda6 was entertaining to toss around, and we never found ourselves worried the car wasn't responding to our inputs. But it's not ready for track duty. It's a sporty sedan, not a sport sedan.

Back on commuter-oriented roads, the Mazda6 was exceedingly competent -- a pleasure to drive. It never exhibited the disconnected (or isolated) driving feel that is so common in the segment. While we did observe some tire roar, and more than a bit of wind noise around the pillars, neither was distracting, nor discomforting.

Looks a bit tall and rides too high, otherwise not bad.

I'd like to see this in Mazdaspeed trim in the future, too.