Sometimes, what a carmaker leaves off is as important as what it puts in. On the new Range Rover Sport, for instance, you will no longer find two 42-pound iron weights hanging off the back corners of the undercarriage. Those weights acted as mass dampers—but they were also a blatant indication that, with the outgoing Range Rover Sport, fat was no object. The new version jettisons the weights, switches from body-on-frame construction to unibody, and trades its steel body panels for aluminum. The result is that the formerly porcine Sport sheds a whopping 800 pounds.

It does so despite increases in overall length (2.5 inches) and wheelbase (7.1 inches). That latter now essentially matches that of the standard Range Rover, although that car is still 5.9 inches longer and 2.2 inches taller. Land Rover was even able to cram in an optional third-row seat, albeit one that's strictly for kids. Buyers looking for true seven-seat accommodations can expect to be ushered over to the Land Rover LR4.

See All 24 Photos

"What we are desperately trying not to do is have it look like a seven-seat car," says Stuart Frith, chief program engineer. No worries there. Instead, the design is a swept-back, smoothed-out update of its predecessor. The interior, too, is an evolution, one that moves closer to the big Range Rover in both style and substance. A full-length glass roof is new, as is the TFT screen with its virtual gauges (in the upper trim models). The cabin is not only richer but also livelier, with available two-tone and even three-tone color schemes. The new Sport preserves the elevated driving position and thin pillars, making for exceptional visibility. As before, this is one of the few vehicles with a beltline low enough that you can comfortably rest your elbow on the windowsill. Access to the rear seat is much easier. Passengers find a more sculpted rear seat that boasts a bit more legroom, but its cushion is somewhat low.

The two powertrains mirror those of the big Range Rover. With either, the Sport feels quicker than before -- it's also more economical. A 3.0-liter supercharged V-6 replaces the normally aspirated V-8 as the standard engine. With 340 hp and 332 lb-ft of torque, distilled via ZF's exemplary eight-speed automatic (in place of the previous six-speed), it's capable if not exhilarating. The factory's conservative 0-to-60-mph time is 6.9 seconds, and the EPA estimates are 17/23 mpg city/highway. The supercharged 5.0-liter V-8 returns as the top engine. Bristling with 510 hp and 461 lb-ft of torque, the eight-cylinder has a robust soundtrack -- with no supercharger whine -- and a remarkable ability to lengthen passing zones. The V-8 chops nearly 2 seconds off the 0-60 sprint, but it does spend more time at the gas pump, with EPA ratings of 14/19 mpg.

See All 24 Photos

The massive weight loss helps the Sport lives up to its name much better than before. Eight-cylinder models further bolster the car's on-road prowess with adaptive damping and active lean control, an active locking rear differential, and torque vectoring via braking. The V-8 also adds an additional mode to the standard Terrain Response dial: dynamic, which alters the adaptive dampers, steering assist, throttle response, and transmission logic. We spent most of our time with the V-8 car, which corners flat and doesn't have the punishing ride of many sporty SUVs. Compared with the big Range Rover, the Sport has quicker steering and better body control, at a cost of some suspension travel.

Even so, the new Sport beats its competitors in this area and is actually better off-road than before. Ground clearance has increased, the variable ride height has a greater range, and the car can wade through deeper water -- up to 33 inches. (Unfortunately, a neat screen graphic indicating the depth of water you're driving through won't be in U.S. cars.) The standard AWD system has a rear torque bias and a single-speed transfer case with a Torsen center differential; the optional system has a 50/50 default torque split and a two-speed transfer case (high and low range) with a locking center differential. Our Sport was fitted with the latter and, on standard Michelin tires, it excelled in every off-road challenge we threw at it: powering through deep mud ruts, driving down the middle of a shallow river, and -- about as likely for most owners -- tackling an obstacle course set up inside a 747.

Writing of the previous Sport, we said: "Unfortunately, the Range Rover can't be a true athlete because it's just too porky." Actually, back then, the Sport maybe could have been a burly nose tackle; now it's more like a fleet-footed running back. Range Rover put a lot into the new Sport, but the most important change is what they took out of it.

See All 24 Photos