If you’re a family man, somewhere out there is the car that you want, and elsewhere — probably in your garage — the car that you “should” want. The lust-worthy power-monger that goes 0-60 faster than you can tie your shoes, with a throaty engine growl and hand-stitched leather — and the sensible choice with decent fuel economy, a tow package, and space for seven. But you needn’t choose between two different vehicles — so long as you’re willing to spend a bit for that sweet spot in the middle. The Mercedes Benz GLS peacefully slots between sport and practical — a German car playing Switzerland — by mating three roomy rows to gleaming muscle. On a drive through Colorado’s mountains and under Utah’s arches, I discovered power cloaked in utility and luxury served family-style. And I played with lots of suspension settings.

To start, let’s get nomenclature out of the way — I promise it’s quite painless. In the US, we have the A-Class, C-Class, E-Class, and S-Class, in ascending order of size and luxury. For SUVs or crossovers, add “GL” to the front. (Note: a G-Class is just a G-Class, and moms happen to love it). So, the GLS supplants the top-end SUV formerly known as the GL, and shares the S-Class moniker with its ultra-luxury-sedan cousin. Is it truly the S-Class of SUVs? Sort of. It has some classic flair, like a buttery-smooth Nappa leather interior, panoramic sunroof, and gleaming 8-inch infotainment display, plus some cute touches, like temperature-controlled cup holders, Apple CarPlay, and power folding third-row seats.

Ultimately, though, its interior lacks the over-the-top awe factor that S-Class drivers have been conditioned to expect. At this level, couldn’t buyers expect a massage on their road trip? Maybe a super-powered sound system or all-digital gauges? Small quibbles aside, the interior is more than adequate in its main mission: hauling people and their things. It has a third row that “fits people with actual legs,” as Mercedes’ head of product management M. Bart Herring put it (my six-foot-three frame concurs). It also offers a maximum of nearly 94 cubic feet of space with the seats down, a number on a par with noticeably pudgier cars like the Infiniti QX80. It’s quiet, too, which is much appreciated, though I have no qualms with hearing an engine like this.

Mercedes-Benz AMG GLS63

2017-GLS-GLS63-AMG-SUV-CGT-D

Engine: 5.5-liter twin-turbo V8
Transmission: 7-spped or 9-speed automatic
Horsepower: 577 horsepower
Torque: 561 lb-ft
0-60 mph: 4.5 seconds
Curb Weight: 5,754 pounds
MPG: 13/17, city/highway
Towing capacity: 7,500 pounds
MSRP: $124,100 (base)

And the engine is where the car differentiates from a crowd of contemporaries. There are many power plant options — a flavor and price for all shoppers. The diesel-powered GLS350d ($67,050), the least costly of the bunch, provides the best fuel economy. The GLS450 ($68,700), expected to be the volume seller, sports a 362-horse V6. Beyond these, things get serious: dads who traded in their sports car for these “family-mobiles” will feel the heavens open as they stamp down the gas pedal.

The GLS550 ($93,850) features a 449-horsepower twin-turbo V8; the handcrafted V8 in the AMG GLS63 ($124,100) gives a generous 577. The 550 moves almost without coaxing and feels almost relieved as you mash the throttle, but the snarling AMG 63 finds a natural resting speed at 85 mph. For a three-seater SUV to have that type of power is both gratuitous and completely revelatory. As a wily auto journalist driving sans children, but with an appetite for adventure, I felt completely unburdened by the car — it didn’t feel heavy, it didn’t balk when asked to accelerate; rather, it crushed desert asphalt with glee, a huge SUV whose acceleration pins the occupants to their seats.

In fact, with a high-performance engine, the GLS seems to take notes from its Geländewagen (G-Class) patriarch, a car that also elegantly mixes function with pleasure. (To investigate this parallel, I had to take the absolutely bonkers G-Class AMG 65 and its 621-horsepower twin-turbo V12 for a spin. Can confirm: bonkers.)

With a high-performance engine, the GLS seems to take notes from its Geländewagen (G-Class) patriarch, a car that also elegantly mixes function with pleasure.

For all its power, the top-end GLS has handling to back it up, though drivers will be grateful that Mercedes has offered loads of customization options by way of their AirMatic suspension. The default “comfort” mode felt a bit floaty for me across all models, as though the weight of the car was following me into a turn. But in sport mode, when the suspension dropped 15mm, it felt just right. The car’s squatting, athletic position was more appropriate winding along the highways of Western Colorado and kept my three-rowed behemoth feeling slim.

There will be a day when a dad is grateful for the GLS’s utility, when he fills all three rows and uses all seven comfortable seats — maybe shuttling the team to soccer practice or the kids to school. But there will also come a time when that same Dad drops the crew off and finds himself with an empty car and an open road. In that moment, the GLS, with its brawny engines, exposed tailpipes and gleaming grille, is both the car he will want and the car he should want.