I’LL go out on a limb and wager that most people who buy three-row S.U.V.’s and crossovers neither know nor care what’s under the skin. That’s fine — who but a car geek cares what lurks beneath a Ford Explorer?

But nearly all of these vehicles are built on shared platforms, and that incurs compromises. Crossovers are typically based on front-drive cars with limited towing and off-road abilities. Body-on-frame S.U.V.’s are based on pickups, and they (including the original Durango) drive and swill fuel like trucks.

The latest Durango, though, is based on neither a car nor a pickup. Thanks to Chrysler’s bygone hookup with Mercedes-Benz, the Durango (as well as the Jeep Grand Cherokee) shares DNA with the Mercedes GL, a classier fancier relative than a Taurus or a Silverado.

Like the $60,000-plus GL, the Durango uses a rear-drive unibody platform with independent suspensions front and rear. This seems the best of both worlds. You get S.U.V. prowess for off-roading and towing without paying a significant penalty in on-road drivability or fuel economy. In fact, a rear-drive V-6 Durango can tow slightly more than a Chevy Tahoe Hybrid while matching its highway mileage rating.

The Durango’s new V-6 puts out a healthy 290 horsepower, but Dodge also offers a 360-horsepower Hemi V-8 that uses a cylinder-deactivation system to run on 4 cylinders under light loads. Most of these deactivation systems seem to work if you’re only heading downhill with a tailwind under a waning moon, but it’s easy to coax the Durango into fuel-miser mode at moderate speeds. On a highway trip during an earlier test of the V-8 Durango, I got 22 m.p.g., which equaled the rating for the V-6 with all-wheel drive.