UPDATE: Since we first published this post on July 9, Motor Trend reader Marc Remington has spotted what appears to be another 2015Subaru Outbackprototype testing in Michigan. Though we've also spied the mechanically related2015 Subaru Legacy sedan, the Outback has been the automaker's best-selling vehicle through the first eight months of 2013, far ahead of every other model except the Forester. Check out the three new spy shots at the bottom of the gallery below.

Despite the camouflage, a more steeply raked windshield and rear window give the Outback prototype a sleeker profile compared to the current model. The prototype features a new hood with thick camo covering two out board character lines. Projector headlights are slimmer, while the reshaped grille opening now features more horizontal slats.

The rugged Legacy-based wagon features its signature off-road style rocker panels, a roof rack, and prominent lower front spoiler. Side mirrors have moved from the pillar to the door, and the Outback prototype sits on blacked out 18-inch alloy wheels. Around back, the taillights appear smaller than those on the current model.

Interior spy shots reveal a new dashboard with a large two-gauge cluster, and a sportier steering wheel with paddle shifters, along with revised HVAC vents.

While powertrain details haven't been revealed, the 2015 Outback will likely be powered by the updated 170-hp 2.5-liter H-4 and new turbocharged 250-hp 2.0-liter H-4 as in the 2014 Forester. It's unclear whether the 3.6-liter H-6 will return. A diesel-hybrid powertrain seen in the Subaru Viziv concept from the 2013 Geneva auto show is also a possibility.

The next Outback is expected to debut at the 2014 Detroit auto show in January, with production starting June 2014.

Photo Source: Chris Doane Automotive,Motor Trendreader Marc Remington