Until recently, BMW didn’t offer a righteous rival for the S-Class Coupe. Subsequently, the Mercedes-AMG S63 was ruling the realm without a competitor in sight, but that changed when the M8 was born.

Although the S-Class Coupe/AMG S63 is a shorter, two-door version of the larger S-Class sedan and the M8 was designed as fully-blown coupe right off the bat, it fits nicely into the same ballpark as the juiced-up Mercedes-AMG S63. So in our quest to see which is better, we’re taking a good close look at what they have to offer on paper.

Exterior

It’s not that hard to see that BMW’s approach for the M8 implies a mean-looking front end dominated by a long hood and slim headlights that run from the grille towards the sides and slightly towards the rear. Below the headlights sit a pair of air intakes and a low, subtly-designed lip spoiler.

The AMG S63 likes its hood long, too, but the stance it imprints on the front end is that of a wider, planted posture, whereas the M8 appears to be more svelte and agile. In the S63’s case, the wide Panamericana grille dominates the front end, while the exquisitely-designed headlamp clusters provide a visual balance for the gaping lower spoiler flanked by extra air intakes that provide better cooling to those massive front brake discs.

When viewed from the sides, the contrasting approaches in design become even more obvious. The M8 looks like a top athlete that’s not afraid to have a stab at bodybuilding whereas the Mercedes-AMG S63 is a finely-carved sculpture on wheels. As you are about to find out in the Interior section, these approaches on exterior design make all the sense in the world in regard to what these two coupes have to offer and the type of customer they are aimed at.

Moving on to the rear, the only similarity between the two heavy hitters is the horizontal positioning of the taillights. The BMW M8 stays faithful to the muscular thematic we’ve mentioned earlier through a rear end that looks like the car is squatting, ready to leap forward. The S63 looks wider and flatter on the road; don’t get us wrong, its rear end is still sculpted, but in complete synergy with the rest of the body, as it displays the same statuesque vibe.

Now that we’ve discussed the aesthetics of the two cars, let’s look at the numbers. The Mercedes-AMG S63 Coupe is 198.9 inches long, while the M8 stretches to 191.8 inches. That’s a 7.1-inch difference in length between the two. Furthermore, the S63 is 83 inches wide, while the M8’s width measures 75.1 inches; so the S63 is 7.9 inches wider. When it comes to height, it’s the S63 that, once again, comes out on top. Merc-AMG’s coupe is 56 inches tall, while the M8 measures 53.6 inches in height - that’s a 2.4-inch difference. Last but not least, the S63’s wheelbase stretches to 115.9 inches, while the M8’s comes in at 111.3 inches, which makes it 4.6 inches shorter.

Interior

We’ve established that while sharing common ground in the amount of performance they deliver, the BMW M8 and the Mercedes-AMG S63 are two very different dishes when it comes to their design. And there’s no better proof to it than their interiors.

Let’s start with the Mercedes-AMG. The flat-bottom steering wheel that wears the AMG logo is a delight to hold. It’s also one of the sleekest you’re going to find on a luxury car, and that contributes a lot to the idea that while you could hire a driver to take you places in your S-Class sedan, the AMG S63 Coupe is yours to drive. The M8’s steering wheel, on the other hand, has that same come-and-drive-me appeal but BMW went for a round shape. It, too, displays the M logo, but it’s a tad thicker and softer; it’s like holding a nearly ripe plum, that’s the best comparison I can think of right now.

The M8 follows in the footsteps of the revised 7 Series and gets BMW’s Operating System 7.0 (that includes the Live Cockpit and the iDrive 7.0) and adopts a digital instrument cluster supported by a multimedia screen positioned on top of the center console. A similar arrangement is found in the S63 AMG, but Mercedes went for the seamless integration of the two tablet-like screens, which have been joined together to form a single, longer unit. BMW kept them separate to one another in the M8 and that’s a sign of just how much the Bavarian coupe wraps around the driver, a typical BMW trait you can experience in every model from the carmaker’s range. That’s not to say the Merc is ignoring its occupants. The movie theatre-like setup is one of the most spectacular in the industry and contributes heftily to the plush cabin of the AMG S63 Coupe.

In the S-Class, both the screen that serves the instrument cluster and the center-mounted measure 12.3 inches. Elsewhere, the dashboard design is also well-defined for each coupe. The Mercedes sports a boat-like topography which makes the cabin feel airy and spacious to a greater extent than what the M8 has to offer. Again, that’s due to each car’s ethos. The M8 wraps around the driver and keeps him or her connected to what’s happening with the wheels, suspension, and steering, while the Mercedes-AMG puts less emphasis on driving thrills as it insists more on the lavishness of the ride - quiet and comfortable, first and foremost. In this respect, the S63 is the ultimate cruiser that can go fast when needed, while the M8 is more like your go-to corner-carving machine that can also cruise around when you want it to do that.

Inside the M8, front headroom is rated at 38.9 inches, while in the rear, occupants get 33.6 inches. The Mercedes-AMG S63, however, offers 40 inches of headroom in the front and 36.7 inches in the rear. The M8 is a tad better when it comes to front legroom (42.1 inches opposed to the AMG’s 41.7 inches), but falls behind in the rear legroom department, where it offers 29.5 inches, a value that’s surpassed by the Merc-AMG’s 33.4 inches. In the shoulder room department, the M8 offers 57.2 inches in the front and 46.9 inches in the rear, while the S63 has to make do with 51.4 inches in the front and 57 inches in the rear. This difference in space in the rear is perhaps the best way to illustrate how the M8 (and the 8 Series it is based on) was designed as a dedicated coupe, while the S63 is derived from the S-Class limousine and thus inherited a more spacious rear area.

Drivetrain & Performance

It cranks out 603 horsepower at 5,500-6,000 rpm and 664 pound-feet of torque between 2,750 rpm and 4,500 rpm. These resources are channeled to all four wheels through the AMG Speedshift MCT 9-speed automatic gearbox and the AMG Performance 4Matic+ all-wheel-drive setup. The configuration allows the S63 to blast from 0 to 60 miles per hour in 3.4 seconds and reach a top speed of 186 miles per hour.

That’s three horsepower and 111 pound-feet less than the S63. Just like in the S63, the engine’s grunt goes to all four wheels, but BMW opted for an eight-speed gearbox in the shape of an M Steptronic automatic unit with Drivelogic tech and Launch Control. You can also switch to full RWD in the M8, but in AWD setup, the BMW M8 goes from 0 to 60 miles per hour in three seconds flat and on to a top speed of 190 miles per hour. That’s 0.4 seconds quicker and four miles per hour faster than the Mercedes-AMG S63.

Needless to say, although pretty similar if we compare their spec sheets side by side, these two cars serve different purposes, different driver personalities, and ultimately, contrasting driving habits and personal preferences. The BMW is sportier if we look at the level of engagement you get behind the wheel or the way the gearbox is set up, while the Mercedes imposes a more laidback experience for the driver with silkier transmission shifts and a quieter ride, but the performance is obviously still there when you need it. What we’re looking at is essentially, a paradox, as the two models are well-equipped in terms of oomph yet the ways they deliver the V-8 grunt is very different.

Which is Better?

As we already mentioned, they’re somehow connected by similar powertrains and on-par performance figures, but otherwise, they serve opposite philosophies. The S63 is definitely the more opulent-looking, luxury-oozing one, but that’s not to say the materials inside the M8 are of a lower status. Not at all. They’re just tailored for another sort of driving experience, a more engaged one, with a lot of emphasis placed on sportiness and on-the-road dynamics you can actually feel. The Mercedes-AMG S63, on the other hand, without sacrificing performance, is tailored for those who care about the way the world sees them but at the same time like to spoil their senses not with the thrill of driving but with the milk and honey brought by plush materials, modern technology, and top-shelf detailing.

To simply put it, we’d buy both cars should we possess unlimited funds, because the fancies they tickle are so different that we’d be swapping them according to our own moods. In need of some adrenalin? Take the M8 and hit the track or go on a road trip to the nearest mountain road. Want to go the long distance and spend your holiday cruising on the French Riviera? Then take the AMG S63 and travel in style while turning some heads in the process. There’s also the price tag to be considered here: the AMG S63 Coupe starts at $169,450, while the BMW M8 is considerably cheaper, at $133,000. Not even the 617-horsepower M8 Competition can touch the S63’s price tag, although it starts at $146,000.