The 2019 Mercedes-AMG GT 4-Door is hungry for Porsche’s lunch

German luxury brands are by now experts at slithering their tendrils into every market segment under the sun, and they even concoct new ones when there’s opportunity. Once Mercedes took the standard E-Class sedan and morphed it into the swoopy, sexy four-door CLS in 2004, the floodgates were open. It was only a matter of time, then, before BMW belched out the aesthetically questionable BMW X6 crossover as a sporty (and less practical) alternative to the X5 in 2008. So now that sporty, four-door, executive-luxury Porsche Panamera is in its second generation, you better believe Mercedes is throwing its feathered hat into the ring.

But this is the brand whose mantra is “The best or nothing,” so simply plopping another AMG motor into the new CLS-Class wasn’t enough. In fact, there won’t be a new CLS63 AMG at all this time around. Instead, AMG is fully taking the reins and introducing its own from-scratch four-door luxury speed demon—the 2019 Mercedes-AMG GT 4-Door Coupe.

The AMG GT 4-Door Coupe is the third vehicle developed entirely by AMG, and the first with four doors, following the now-retired SLS AMG and the current AMG GT two-door. But while Mercedes’ marketing team would like you believe its four-door AMG is just a bigger, more spacious, and practical GT (as Mercedes would also like to convince you a car with four doors can be called a coupe) the car in fact rides on an entirely different architecture. Instead of the bespoke platform used for the AMG GT coupe and convertible, the 4-Door underneath shares its bones with the E-Class.

Looking at the GT 4-Door, however, you’d never be able to tell. It features a completely all-new design inside and out, complete with a hood and front fenders made of aluminum, while its rear firewall and trunk floor employ carbon fiber. Up front is an active aerodynamic system with 20 vertical fins in the front bumper designed to optimize airflow and cooling, while the rear features a multi-stage extendable spoiler that automatically responds to the selected drive mode and vehicle speed to provide necessary downforce and drag reduction.

There are two engine flavors for the AMG GT 4-Door, including the tried-and-true twin-turbo 4.0-liter V-8 engine that’s been the standard-bearer for AMG in everything from the G63 off-roader to the small-but-mighty C63 AMG. As in the GT coupe it will be offered in two states of tune, starting with a GT 63 model good for 577 hp that equals output from the Nurburgring-slaying AMG GT R. King of the hill is the AMG GT 63S 4-Door, which is the most powerful Mercedes in history with its stunning 630 hp and 664 lb-ft of torque. Cog-swapping for these beefy engines is the duty of a nine-speed automatic transmission with a multi-plate wet clutch. The 63 S accelerates from 0–60 mph in just 3.1 seconds, the 63 in 3.3.

New to the party is the 3.0-liter turbocharged inline-six for the AMG GT 53, which replaces the outgoing generation of Mercedes V-6 engines. Shared with the new CLS 53, the straight-six makes a healthy 429 hp and 384 lb-ft of torque. An advanced starter/generator sitting between the engine and transmission also functions as an electric motor which can add an additional 21 hp of boost, particularly at the low end of the rev range where it is meant to step up while the turbocharger spools. For the six-cylinder 53 model, the transmission is a torque-converter version of the same nine-speed used in the 63 and 63S, and 0–60 mph happens in 4.4 seconds.

Our drive route in the AMG GT 53 amid the winding roads bordering Austin, Texas gave us our first taste of how this newest AMG performs. Most impressive is the totally seamless hand-off between the so-called EQ Boost electric motor and the silky smooth inline-six, which is more than powerful enough for daily driving duties and spirited weekend drives. GT 53 models come standard with steel springs and adaptive dampers, which strike just the right balance between ride and handling for a luxury car with this sort of sporting ambition.

The interior, too, is a total home run. The dizzying array of high-resolution screens, leather, and carbon fiber trim create a show-stopping cockpit that feels legitimately special every moment behind the wheel. As in the Porsche Panamera though, there is a bit of information overload as a result of so many settings, screens, buttons, and selectors—especially when the focus should really be on the driving. Golfers will love the GT 4-Door’s liftback layout, which features a foldable rear seat when the executive rear seat package is equipped. Two fixed rear bucket seats with carbon-fiber seatbacks come standard.

Less successful is the car’s exterior. Like the original Panamera which looked like a bloated, stretched 911, the GT 4-Door is more of a hodge-podge of Mercedes and AMG styling cues than a cohesive design. It’s hard to find a particularly flattering angle, and the fixed rear wing on the optional aerodynamic package does it no favors either. Nevertheless, it is recognizable as a stylish, large-and-in-charge Mercedes meant to command a bit more attention than the famously subtle S-Class.

Let loose on the race track, though, it doesn’t take much effort to rip around so fast that you’ll appear as a blur to onlookers. All versions of this car come with 4Matic all-wheel drive, and GT 63 S adds to that air suspension, rear-wheel steering, and an electronic limited-slip differential. The result is a fierce blend of raw power, control, and comfort that is downright marvelous to spank around a road course.

Weight isn’t yet available for U.S.-spec cars, but the European pre-production cars we drove come in at 4508 pounds, and somehow that’s the farthest thing from your mind on the track. Yes, the GT 4-Door feels big all the time, but it’s remarkably controllable at speed. The rear-wheel steering, which turns the opposite direction of the front wheels below 62 mph and the same direction as the front wheels past that, makes the GT a lot more maneuverable than you’d expect it to be, while the all-wheel drive and limited-slip differential make it a cinch to claw out of corners. And on a long straight, life is as simple as stomping your foot and listening to the burly growl of Affalterbach’s finest. When the corner ahead comes into view, optional carbon-ceramic brakes bring things to a halt, without issue, lap after lap.

No doubt the GT 4-Door will be a rare sight at weekend track days compared to the more focused two-door GT and GT R, but the guiding hand of AMG in the new car is clearly evident. The 4-Door may share more name than platform with the AMG GT, but it’s more than worthy of the moniker. The Porsche Panamera Turbo is in good company,

The AMG GT 4-Door Coupe will launch in early 2019 first in 63 and 63S guise, with the 53 model to follow. Pricing is yet to be determined, but it’s a safe bet the GT 53 will start at right around $100,000, with the 63 and 63S stretching the budget to perhaps the $130,000–$140,000 range.