2021 Mercedes GLS450 Review

Lots of medium-large crossovers offer a third row. Almost all of them offer very little room in that row.

It’s the dilemma of room vs. size.

The Mercedes GLS is among the few with size and length that has the room you’d otherwise have to buy something bigger (and longer) to get.

It’s also got some other things way back there, including heaters for the third row.

And there’s something else, too.

Two of them, actually.

What It Is

The GLS is a three-row ultra-luxury crossover SUV that fits in places a full-size sedan like the Mercedes S-Class would find tight while fitting several more people inside.


It has nearly 35-inches of legroom in its third row, which is about 4-inches more than is typical in the third row of most crossovers its size (and length) that offer a third row. There are only a handful of crossovers in the same class as the GLS that can also compete with it as far as space—the BMW X7 is probably the closest. Like the big Benz, the BMW offers a roomy third row and comes standard with a turbocharged inline six-cylinder engine, teamed up with a mild-hybrid set-up that cycles the gas engine off and on as you drive to decrease the amount of gas you burn as you drive.

But the Benz offers something else, a twin-turbo V8 with two versions—a 483 horsepower version and a 603 horsepower version.

It’s hard to find anything that can carry seven people that fast.

Prices start at $76,000 for the six-cylinder (and partially electric) GLS450, which comes standard with Mercedes’ 4Matic all-wheel-drive system, an adaptive suspension system, full-length LCD dashboard, and a Burmester premium audio system.

The $98,850 GLS 580 includes a 483 horsepower twin-turbo V8, standard massaging driver and front passenger seats, and five-zone climate control.

If you have $132,100 burning a hole in your pocket and want to burn some rubber, there’s the GLS63 AMG, defined by the 603 horsepower twin-turbo V8 under its hood, plus upgraded brakes and a more aggressively tuned suspension to match.

What’s New

This Benz got a complete makeover last year, probably to put some more distance between it and its chief rival, the BMW X7, which was all-new in ’19.

The main change for 2021 is adding the 603 horsepower GLS 63 AMG to the roster, probably to put the 523 horsepower X7 M50 a bit farther in the rearview mirror.

On deck is a $200k Maybach version, if that’s not enough, with reclining and massaging rear seats.

What’s Good

  • An S-Class for seven.
  • The third row isn’t coach class.
  • Standard six; two available V8s.

What’s Not So Good

  • An excellent E-Active Body Control system is only available with the much-more-spendy GLS 580.
  • Like the X7 (and the also similar but slightly smaller Lincoln Aviator), there’s no Low range gearing; if you need to take seven off-road, you’ll need an SUV with truck-type underpinnings such as the Cadillac Escalade, Range Rover Sport, or the Lincoln Navigator.
  • Even though it can cycle its gas engine off, gas mileage isn’t that great: 20 city, 24 highway.

Under The Hood

Like several other Mercedes models, including the E-Class sedan I recently reviewed, the GLS comes standard with a 3.0-liter straight six augmented by a generator/starter system (and 48-volt electrics) that’s used to regularly cycle the six off and on to boost gas mileage and lower gas (carbon dioxide) emissions.

The latter is the bigger deal for Mercedes and other manufacturers trying to keep gas-burning engines under the hood at all. Not because buyers don’t want them but because government regulations are getting to the point of almost outlawing them.

When a gas engine isn’t running, it emits zero emissions, just like an electric car (well, just like an electric car at the tailpipe). But unlike an electric car, the GLS continues running and without waiting.

You gas it up just as you always have in the past. The engine recharges the battery pack, spinning the flywheel starter, which cycles the gas engine back whenever you need to go. It is an elegant solution to a difficult problem.

You don’t have to stop for an hour, either every 200 miles or less, to recharge.

The other boon is not noticing the gas engine cycling off and back on. As is very noticeable in cars without the high-powered restart system the Benz has, and that has instead what is marketed as auto-stop/start “technology.”

It’s like lipsticking the proverbial pig, if you ask me.

Auto-stop/start is a crude way to make the government happy, i.e., to comply with government regulations regarding vehicle emissions. The gas engine shuts off automatically, pretty much every time the vehicle stops moving, and then automatically restarts when it’s time to get going again. The system uses the same basic starter motor used to start IC engines for the past 120 years paired with the same basic 12-volt electrical system used in cars for the past 60 years.

Neither system was designed to restart the engine repeatedly nor do it without any feel or sound of starting.

In the Benz, you don’t. The six is as smooth as an electric motor, without the drawbacks of just an electric motor. The high-voltage restart system directly spins the engine via the flywheel itself rather than a small starter motor spinning the flywheel—restarting it just as smoothly and just as silently.

EPA says 20 city, 24 highway, which isn’t great, but then again, it’s pretty good for a plus-sized, seven-passenger crossover with 362 horsepower under its hood that can get to 60 in 5.8 seconds. We take that kind of speed almost for granted.

We ought to revel in it.

If you need more speed, the V8-powered GLS580 delivers it courtesy of the 483 horsepower twin-turbo’d V8 under its hood. It gets to 60 in just over 5 seconds. And if that’s not enough speed, the GLS 63 AMG’s 603 horsepower V8 gets you there in 3.6 seconds, which is genuinely ludicrous speed without the ludicrous wait.

The GLS is also stout as far as towing. It comes with a standard 7,700 lb. rating.

On The Road

The main thing the GLS offers is executive-class travel for everyone. Not just the driver and passenger with maybe business class for the second-row passengers. And steerage for the third-row unfortunates.

That’s rare, even among other high-end crossovers like the BMW X7, which is slightly smaller and, for that reason, less roomy.

The other thing the Benz offers that larger SUVs with viable third rows do not is a nearly flat floor, which allows for a center aisle rather than a center hump, which most SUVs have because most are built on truck-type chassis, with a separate steel frame, and a body bolted on top of it. The hump running down the centerline makes space for the driveshaft at the expense of space for the passengers—and not just for their legs.

It’s harder to maneuver to get into and across the seats with that hump in the way. In the Benz, it’s not.

Once you’re rolling, you’ll appreciate the handling, which is remarkably adept given the size of the GLS. It is like driving an S-Class, just higher up and with more behind you.

The only deficit here is that even better handling is available, but only if you spring for the more expensive GLS 580, which can be ordered with Mercedes’ very trick E-Active Body Control system. This system leans the body back toward the inside of the curve to counteract the tendency of the body to roll toward the outside of the curve during high-speed cornering.

It also scans through the road ahead for irregularities like potholes. It pre-adjusts the suspension calibrations in anticipation of them, rather than reacting to them after you’ve already driven over them.

The 48-volt electrics and infusion of electric motor instant-on torque imbue the Benz with the immediate thrust that people admire entirely electric cars for, without worrying about when you’ll run out of juice that makes people leery of entirely electric cars. Plus something else: The intangible emotional appeal of that inline-six.

These engines have a different character than any motor. Or any V6. They are smooth and revvy and make you feel happy—you’ve achieved a degree of success in life and for that reason can treat yourself to something like this.

The treat is even more so with either of the two available V8s—especially the version in the GLS 63 AMG.

If being able to keep up with a Corvette with seven people on board doesn’t make you grin like the Joker, there’s something awry with your sense of humor.

At The Curb

You can go to six or seven seats.

Benz offers both configurations, with captain’s chairs for the six-seat layout. Either way, they all fold flat at once at the touch of a single button. Or individually, as you prefer. An available Executive Package includes a fold-out/down center console, tablet to control the infotainment/climate, and heaters for the all-the-way-in-the-back seaters. That’s a uniquely Benz luxury amenity, sure to be emulated but, for the moment, exclusive.

Similar to the S-Class is the dash layout of the GLS, an all-flat-panel LCD touchscreen display that can also be configured by voice. Just say, “Hey, Mercedes.”  Then tell it what you’d like it to do, such as change the audio selection or turn on the massaging seats.

Something else the GLS has that the S-Class doesn’t is a pair of heated grab handles on either side of the center console, with heated metal trim surrounds that radiate heat to your sides without having to grab them.

Such things spoil a guy.

Mercedes also has arguably the best LED mood lighting. The entire cabin is bathed in an ethereal aura of light, your pick of the spectrum. If they had this in the ’60s, they’d have called it trippy.

Also retro, but smoothly blended with the very modern look, are pewter-plated toggle switches for several everyday/important functions, which you can use if you prefer rather than “Hey, Mercedes,” or tap/swiping through the screen or via the mouse trackpad in between the grab handles.

There are nine USB power points.

The enormous panorama roof is, as a friend put it, surf worthy.

The Rest

The GLS is also an exciting midway between the typical crossover, typically based on a light-duty and usually FWD-based car layout. As discussed above, the typical SUV is based on a burly truck layout, with four-wheel (rather than all-wheel) drive and 4WD low-range gearing.

It’s more rugged and capable than most crossovers, which aren’t designed for more than light-duty towing, especially. But it’s not as capable of going off-road as an SUV, which has the gear for that kind of duty.

What you have is a ride that doesn’t feel flimsy and handles athletically that can pull a pretty heavy load without feeling clunky in the curves and without the hump on the inside.

With everything you can get and expect in an S-Class. And room for seven people or a lot of stuff (84.7 cubic feet with the second and third rows folded, almost enough to store an S-Class).

The Bottom Line

Luxury for more is what this Benz is all about — and delivers.

Eric Peters lives in Virginia and enjoys driving cars and motorcycles. In the past, Eric worked as a car journalist for many prominent mainstream media outlets. Currently, he focuses his time writing auto history books, reviewing cars, and blogging about cars+ for his website EricPetersAutos.com.

Editor’s Note: The opinions expressed in this article are those of the author.

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