Mercedes-Benz is working on a mid-cycle update for its GL-Class that will see the full-size luxury SUV rebranded a GLS in line with the automaker鈥檚 latest naming scheme. Like the GL, the new GLS will feature a high-performance variant developed by Mercedes-AMG, a prototype for which has been spotted once again. The new performance variant will be badged a GLS63, and its basic specifications should be similar to those of the GL63 it will replace. This means a twin-turbocharged 5.5-liter V-8 mated to a seven-speed automatic transmission and drive going to all four wheels. Peak output in the GLS63 should match the 550 horsepower and 516 pound-feet of torque delivered in the mid-size GLE63 that was just launched on the market. We may also see a slightly more potent S model this time around. This potential GLS63 S should match the 577 hp and 561 lb-ft offered in the GLE63 S, and will almost certainly better the 4.9 seconds it takes the current GL63 to reach 60 mph. Top speed should remain governed at 155 mph. While there aren鈥檛 expected to be many powertrain mods, the exterior will receive a substantial makeover. We can already see that the new GLS range, including this GLS63, will feature a new hood, a more rounded front end and revised head and tail-lights. We also know that plusher materials, more electronic driver aids and a more advanced infotainment system will feature in the cabin. We should have more details soon, as the updated GLS range is due to be revealed late this year or early next. The vehicles are expected in showrooms by next spring, as 2017 models.

Mercedes-Benz is working on a mid-cycle update for its GL-Class that will see the full-size luxury SUV rebranded a GLS in line with the automaker鈥檚 latest naming scheme. Like the GL, the new GLS will feature a high-performance variant developed by Mercedes-AMG, a prototype for which has been spotted once again. The new performance variant will be badged a GLS63, and its basic specifications should be similar to those of the GL63 it will replace. This means a twin-turbocharged 5.5-liter V-8 mated to a seven-speed automatic transmission and drive going to all four wheels. Peak output in the GLS63 should match the 550 horsepower and 516 pound-feet of torque delivered in the mid-size GLE63 that was just launched on the market. We may also see a slightly more potent S model this time around. This potential GLS63 S should match the 577 hp and 561 lb-ft offered in the GLE63 S, and will almost certainly better the 4.9 seconds it takes the current GL63 to reach 60 mph. Top speed should remain governed at 155 mph. While there aren鈥檛 expected to be many powertrain mods, the exterior will receive a substantial makeover. We can already see that the new GLS range, including this GLS63, will feature a new hood, a more rounded front end and revised head and tail-lights. We also know that plusher materials, more electronic driver aids and a more advanced infotainment system will feature in the cabin. We should have more details soon, as the updated GLS range is due to be revealed late this year or early next. The vehicles are expected in showrooms by next spring, as 2017 models.

Air suspension and magnetorheological dampers are pretty fancy, but the Lexus has a hydraulic setup, a tiny bit like Citro ns of yore! The LX 570's trucklike nature splits the judges' opinions. No, but four 鈥?the QX80, Range Rover HSE, LX 570, and GL450 鈥?are very good. The weakest SUV here makes 340 horsepower. That would be the Range Rover with its supercharged, 3.0-liter V-6. Remember, though, the Range Rover has less mass to move, and as such its straight-line prowess is solidly mid-pack at 6.3 seconds to 60 mph. The QX80 also hits 60 mph in 6.3 seconds, while the Lincoln and the Mercedes both do it in 6.2 seconds. The slowest SUV to 60 mph is the 7.0-second Lexus, while the quickest is the Escalade, which gets it done in a tidy 5.9 seconds. The Cadillac also wins the quarter-mile battle, doing so in 14.4 seconds at 96.8 mph, while the Lexus once again brings up the rear, running the quarter in 15.4 seconds at 90.8 mph.

The Escalade has the worst braking performance (133 feet to stop from 60 mph), but the braking champ Infiniti only stops 10 feet shorter from 60 mph and we've stopped plenty of sporting sedans in a similar distance. Off the test track, the judges' subjective impressions of the six SUVs are worth noting. We all love the Cadillac, and while it's not an actual performance metric, the burbly rumble of the big 6.2-liter V-8 has us all swooning. All of us are impressed by the Lincoln's EcoBoost mill, a sporty 3.5-liter, twin-turbo V-6. We also like the Infiniti's big motor. Despite its worst-in-test numbers, the Lexus actually feels pretty good on the street in terms of acceleration. However, its brake pedal feel leaves something to be desired. The GL450 has a new 3.0-liter, twin-turbo V-6 that has no trouble hanging with the big boys. Going off preconceived notions, you might expect the Range Rover to be the athlete of this group, but it simply isn't on the street.

The only thing I'll add is that this isn't the Range Rover's top engine. If power is what you seek, pony up for the 510-horsepower, supercharged, 5.0-liter V-8. Same (of course) goes for the Mercedes. Not only is there the 429-hp GL550 but also the whack-a-doodle, overkill GL63 AMG that kicks out 550 hp of unnecessary fun. There's no way to put this kindly, but if you're a Prius fan, it's best to skip this part. According to the EPA, the most efficient vehicle here is the Range Rover. The Feds rate it at 17/23/19 mpg city/ highway/combined. Our Real MPG results for this group are not pretty. The Range Rover falls considerably to 14.4/19.9/16.4 mpg. Quite the plunge, don't you think? The others don't fare much better. The Escalade is EPA-rated at 15/21/17 mpg but actually achieves 14.1/20.5/16.4 mpg. The QX80 is rated at 13/19/15 mpg but in the real world nets 12.5/17.9/14.5 mpg. The Navigator is rated at 15/20/17 mpg but actually records 13.9/18.1/15.5 mpg.