So, what's next for the Pathfinder? After earning its place in the market as a body-on-frame model, becoming unibody in its second gen, and going back to body-on-frame for the third, the 26-year-old Pathfinder will again be a unibody for its fourth generation.

The timing makes sense, as the Durango and Explorer went that way and more vehicles may do the same. Also, there is increased pressure to improve fuel economy, which is easier to do when traditional SUV underpinnings are swapped out for unibody construction. While we haven't yet seen the production version of the Pathfinder, which shares its platform with the Infiniti JX, Nissan unveiled the concept at the North American International Auto Show in Detroit, and showed it again at Chicago a month later. We expect this concept to be close to what you'll see in Nissan dealerships starting in fall 2012; it's said to be one of 20 new or redesigned products to arrive within the next two years.

The styling of the fourth-generation Pathfinder is a dramatic departure from the boxier sport/utilities that preceded it. Improved fuel economy was a high priority for the designers, and that meant working on improving airflow above, around, and below the vehicle.

This new generation also gave engineers and designers the opportunity to make the Pathfinder more refined and upscale. As Tom Smith, Nissan's chief marketing manager, explained at the Detroit show, "Owners' lifestyles and their needs have changed over the last few years, from wanting something more rugged, off-road, and truck-like to having something that offers more fuel economy and something that's better on-road while offering more style, more substance, more refinement in a vehicle while still maintaining some level of capability."

From what we can tell, the new Pathfinder has a seven-passenger layout -- 2/2/3 -- and Nissan teased that the sport/utility will have generous legroom in all three rows. Also, judging by the concept, the interior will be significantly more upscale than the current generation's. Based on the JX's dimensions, we'd guess the new Pathfinder will be 4 inches longer, 4 inches wider, and 5 inches lower than the third gen. It is also likely to provide more cargo volume in a more versatile cabin.

Power options are also undergoing major changes. The hearty 266-hp, 288-lb-ft 4.0-liter V-6 and 310-hp, 388-lb-ft 5.6-liter V-8 are expected to be replaced by a single new V-6, backed by a continuously variable transmission. If it's anything like the upcoming JX, that engine will be transversely mounted and put out about 265 hp at 6400 rpm and 248 lb-ft of torque at 4400 rpm, although it wouldn't be a stretch to imagine Nissan would use a detuned version of the Infiniti engine.

The company anticipates that the Pathfinder could be one of the most fuel-efficient seven-passenger vehicles on the market, with a 25 percent increase in combined fuel economy over the 4.0-liter. If that's the case, fuel economy could be as good as 17/25 mpg city/highway (current V-6 fuel economy is 14-15/20-22 mpg city/highway), and would clobber the current V-8's 13/18. But despite the assurances that this is a no-compromise vehicle, we fear the new refinement and fuel efficiency will come at a price. We don't know yet what the towing capacity of the fourth-gen will be -- Nissan says it will be competitive with the segment leaders -- but, more important, we don't know how capable it's going to be off-road.

The current Pathfinder has low range, but its front-drive-based replacement surely will not. Expect additional electronic AWD locks, hill-descent controllers, and so forth to attempt to preserve some off-road cred. Truck Trend readers will likely have to recategorize the fourth-gen Pathfinder as an all-weather soft-roader, but perhaps Nissan will surprise us.