2020 Mercedes-Benz GLS 580 First Drive Review.

The GLS has two new (and rather complex) engines, a 3.0-liter turbocharged inline-six making 362 horsepower and 369 pound-feet of torque and a 4.0-liter twin-turbo V8 making 483 horsepower and 518 pound-feet of torque. Both are paired with a 48-volt mild hybrid system Mercedes calls EQ Boost, increasing fuel efficiency and performance. Both systems work the same way. A small electric motor is placed between the engine and transmission and performs a variety of tasks, from smoothing out shifts to mitigating turbo lag by supplying a bit of low-end power while exhaust gasses spool the turbos. It even powers the accessories, meaning these engines are beltless. That makes them more compact, but it also means there's less parasitic loss from accessories such as the A/C compressor. This is the first time the system is available with a V8 engine, but expect the powertrain to expand to much of Mercedes' lineup over the next few years.

 Like in those other cars, the GLS' power delivery is smooth and linear, with lots of low-end torque to help you off the line and move through traffic. With the kick of torque and lack of turbo lag, these don't feel like other small-displacement turbo engines, including those from Mercedes. There's power all over the rev band, and while fuel economy ratings haven't been revealed, expect a significant improvement over last year's model. While the new V8 in the GLS 580 is knockout, with effortless power and a throaty exhaust note at full bore, the 3.0-liter in the GLS 450 is offers plenty of power day-to-day and is a good value on its own.

All GLS models send power to all four wheels through a nine-speed automatic transmission. It's smooth and unobtrusive like any good automatic should be, and it's right there with ZF's seemingly ubiquitous 8HP 8-speed automatic in terms of refinement.

The new four-wheel drive system is far more noteworthy. The old GLS' system had a fixed 50:50 front-to-rear torque split, but the new model is fully variable, sending 100-percent of the power to the rear wheels in most situations and up to 50-percent of the power to the front when needed. It should help improve traction in all situations, but on loose surfaces like sand, gravel or dirt, it's pretty damn easy to induce oversteer to help the rear of the 17-foot-long SUV rotate like a vehicle half its size. It's amazing just how nimble the GLS feels, especially off road or on tight switchbacks. The turning radius is extremely tight, making it feel and drive like a much shorter and narrower vehicle.

While no GLS owner is actually going to be doing any serious off-roading, the GLS is plenty capable, especially with the new off-road package. The package includes a real, legitimate low range for better crawling and an enhanced Off-Road+ mode that adjusts things like throttle response, suspension and transmission tuning. The GLS also includes hill-descent control and adjustable ride height. All told, the GLS is similar to the Range Rover in that it's far more capable than it realistically needs to be.

The new engines and four-wheel drive system are great, but the single most impressive thing about the 2020 GLS is the ride. The standard air suspension offers a smooth and isolating ride for such a big SUV, but the optional E-Active Body Control is something really special. It's a complicated system (if you haven't gathered it by now, most of what makes the GLS good is complicated), but the basic premise is that a camera reads the road ahead and pre-loads the suspension for any imperfections. Unlike some reactive systems, this knows what's coming up ahead, smoothing out imperfections and potholes like they aren't even there. Expected to work well on the pavement, but the way it seemingly flattens out a dirt road is truly transformative. While it's mainly responsible for improving ride, E-Active Body Control can help you get unstuck in mud or sand. It looks a bit goofy bouncing up and down like an Impala in a '90s music video, but it works.