Rumored for more than two years now, the four-door version of the Mercedes-AMG GT sports car finally broke cover at the 2018 Geneva Motor Show. However, it turns out that the GT 4-Door is exactly a sedan version of the already popular coupe. The four-door model not only uses a different platform that the sports car -- based on that of the midsize E-Class -- but it also looks a bit different front and rear. While this isn't necessarily an issue, the fact that it's very similar to the recently unveiled CLS has ignited some debate on whether Mercedes-Benz was a bit lazy in the design department.

Granted, the two cars are far from identical, but there aren't many differences to talk about inside and out. That's why we decided to bring them side by side for a proper comparison. Of course, with the AMG GT 4-Door being the more performance-oriented model, a proper comparison isn't possible, but fortunately, both models come in "AMG 53" spec. Let's have a closer look at what sets them apart on the outside, inside the cabin, and under the hood in the comparison below. Does it make sense for Merc to offer both? Leave your comments in the box below.

Continue reading for the full story.

The Looks

Having already seen the new CLS, I must admit that the GT 4-Door Coupe looks awfully familiar. But there are a few details that set them apart. Up front, the GT 4-Door gets a more aggressive grille and bumper section. Even in AMG CLS53 spec, the four-door coupe looks milder than the GT-badged sedan. Not only the latter gets the aggressive "Panamericana" grille and a much larger star emblem, but it also sports a more menacing bumper. Sure, the grille shape is similar on both cars, but the vertical slats on the GT 4-Door have a more powerful impact on the eye.

Similarities continue below as the bumpers of both cars sport a three-vent layout, but again, the GT 4-Door looks decidedly more aggressive as the side intakes are notably larger and the center vent has a sharper edge. The headlamps are different too. Both seem somewhat based on the AMG GT sports car, but while the CLS' are sharper and thinner toward the fender, the GT 4-Door are wider in that area. Overall, the latter has the bigger headlamps and it seems as if Merc paid special attention to this detail in order to set the two apart.

Moving onto the sides, it's actually pretty easy to mistake the cars between them if you don't pay close attention to the details. Granted, there's the rear wing as a pretty big giveaway on the GT 4-Door, but other than that, you have to look really close. The beltline, the wheelarches, and the side skirts are similar, the roofline is almost identical, and the door handles and mirror caps are difficult to set apart. But there are two key differences to talk about. One is the small vent on the AMG GT 4-Door's front fender, while the second one, more obvious this time, lies in the sape of the rear door window. More specifically, the GT 4-Door has an actual quarter window, which extends the greenhouse a bit more toward the rear.

If the two are pretty similar up front and onto the sides, they are actually significantly different around back. And it's not just the wing and the more muscular haunches of the GT 4-Door that catches the eye. The latter also has a shorter decklid and longer taillights that are closely related to the AMG GT sports car. The fact that the 4-Door also has a tailgate instead of a conventional trunklid also makes a big difference. The bumpers are all that different, especially since both cars have big vents onto the sides, but the GT 4-Door benefits from the more aggressive diffuser and the bigger tailpipes.

All told, the cars are disappointingly similar from design standpoint, but Mercedes made sure that they can compete in different niches. While the CLS remains a rival for the BMW 6 Series Gran Coupe and the Audi A7, the AMG GT 4-Door can take on the more powerful and dynamic versions of the Porsche Panamera. I'm not really sure that Mercedes actually needed a four-door version of the AMG GT, but hey, I'm not here to judge the company's marketing strategy.

The Interior... Meh

If the two cars have subtle differences and notably dissimilar rear ends on the outside, things aren't as varied inside the cabin, where everything but the center console and the seats is pretty much identical. It may have something to do with the fact that both vehicles ride on the same E-Class platform, but Mercedes clearly didn't put too much effort into this.

Ignore the different colors of the dashboard, door panel, and air conditioning vents trim and you're looking at exactly the same layout. Even the steering wheels are similar on the AMG GT 4-Door and AMG CLS53 models, although the former gets carbon-fiber trim. Is there anything that makes them different? Well, the instrument cluster is slightly different in the GT 4-Door, as are the graphics of the infotainment system. The AMG GT 4-Door also gets sportier seats with bigger side bolstering and the center console from the AMG GT sports car.

Basically Mercedes took the interior of the E-Class, which is also used in the CLS, and spiced it up with a few features from the AMG GT two-door. Not exactly inspiring, right?

The Performance. Finally Something Different

This where the two cars are actually significantly different. Or should I say it's where the AMG GT 4-Door starts and where the CLS leaves off. As you may already know, the CLS was launched with a turbocharged, 3.0-liter six-cylinder engine with a 48-volt electrical assist system that works like a mild hybrid. In base CLS450 trim, it makes 362 horsepower and 369 pound-feet. Then there's the AMG CLS53, which uses the same drivetrain with EQ Boost, but rated at a more solid 429 horses and pound-feet of torque.

The latter is available in the AMG GT 4-Door too. This model goes by the name AMG GT53 and has the exact same power rating and an identical 0-to-60 mph sprint time of 4.4 seconds. Next up is the AMG GT63 version, which draws juice from the familiar 4.0-liter V-8 offered in most AMG cars. The twin-turbo unit cranks out 577 horsepower and 533 pound-feet of torque. Finally, there's the range-topping AMG GT63 S, which comes with a whopping 630 horsepower and 627 pound-feet of twist, significantly more than the track-ready AMG GT R. In addition to the extra power, the AMG GT 4-Door also gets the optional electronically controlled limited-slip differential and the rear-wheel steering system from the two-door AMG GT.

If you've been wondering why Mercedes-Benz has yet to announce AMG CLS63 and AMG CLS63 S model, it's because there won't be any. Performance-wise, the AMG GT 4-Door is some sort of upgrade to the CLS. And that's a good thing, as it would have been awkward to have both cars with the same specs. Especially in terms of marketing.