Few luxury carmakers have a more comprehensive range of vehicles than Mercedes-Benz, but until now, it’s never launched a rival to Porsche’s Panamera 4-door sports car. For 2019, the challenge is finally being taken up with the exciting new Mercedes-AMG GT 4-Door.

Like the 2-seat AMG GT that inspired it, the 4-door model is produced by AMG, a wholly owned subsidiary of Mercedes-Benz that started out life as an independent race car tuner. Most Mercedes models have AMG performance variants but the GT is an AMG creation.

Although at first the new car looks a little like the AMG GT Coupé with its 1950s racing car-inspired grille, it’s endowed with bodywork of its own. AMG did not simply stretch the Coupé body and raise the height a little. It reworked the entire car. The look is very dramatic indeed and as about as sleek as a 4-door car could possibly get. Critics have pointed out that it’s a better execution of a 4-door sports configuration than what Porsche achieved with the Panamera.

There are three engines, though these may not be available in all countries. At the entry-level point, the GT53 uses a new 3.0-litre turbocharged inline six with 429-horsepower, a remarkable achievement for a 6-cylinder engine and certainly aided by a supplementary 48-volt electric motor. Move up a slot and you get a GT63 4.0-litre V-8 with twin turbos that generate a solid 577-horsepower. At the top of the power range is another 4.0-litre V-8, but this GT63 S is tuned to deliver a whopping 630-horsepower, making it the most powerful car AMG has ever created. All models use a 9-speed automatic transmission of very advanced design.

The car is equipped with exceptionally powerful brakes that keep all that power in check, but buyers can opt for even more effective ceramic brakes that are perhaps more suitable for track driving. We’ve found that carbon or ceramic brakes have a tendency to squeal in everyday use and this can be distracting. Perhaps the best safety feature of this car is the standard all-wheel drive that gets power to the road exactly where and when it’s needed.

Unusually in a car like this, the AMG GT 4-Door offers different seating configurations to suit the needs of individual owners. Although most buyers would probably go for the pair of seats in the rear that’s common in 2+2 layouts, it is possible to order a rear bench seat that will accommodate three people, preferably small ones. Rear occupants can select various comfort features with a touchpad screen located on the console between the seats. Like the Porsche Panamera, the GT 4-door has limited rear headroom; the price to be paid for any car with dramatically styled bodywork like this.

The cockpit is something of a high-tech feast with every possible practical and convenience feature. Beautifully fitted out and finished, as is even the least expensive Mercedes-Benz product, even the steering wheel is a masterpiece of advanced design. Various functions are combined in groups and touch and feel can be controlled using buttons, also on the steering wheel. Finger swipes are used to operate the infotainment system, a process that takes a little getting used to.

This new AMG is certainly one of the most interesting cars to emerge from Germany in some time. It offers stunning performance in a package that could qualify it as a family car, yet tests at the fabled Nurburgring circuit have proved even the basic model as an amazing performer. On the design front it’s a real head-turner and the interior has an ambiance to match any luxury rival. It probably won’t be a volume seller for Mercedes, but it’s bound to be widely praised and admired.

ENGINE: 4.0-litre V-8, 630-horsepower twin-turbo (top model).

TRANSMISSION: 9-speed automatic, all-wheel drive.

ACCELERATION: 0 to 100 km/h in 3.4-seconds (top engine option).

TOP SPEED: 315 km/h.

I LIKED: Very dramatic styling inside and out and exceptionally well put together. Awesome performance, even at the basic 6-cylinder engine level. Excellent brakes and handling.

I DIDN’T LIKE: Perhaps understandably, headroom is limited at the rear, but there’ll be no complaints from the kids.

MARKET ALTERNATIVES: Porsche Panamera GTS, BMW 6 Series Gran Coupé.

WHO DRIVES ONE? Luxury sports car enthusiasts who’d like to take the whole family along now and again. People who have tired of the limited cockpit and cargo space that comes with most two-seaters and desire sometime a little roomier without a performance sacrifice.

PRICE AND AVAILABILITY: Available now starting at €135.700.