Is the M8 Gran Coupe just another niche four-door coupe or is there more to it?

LISTEN 15:34

The BMW M8 Gran Coupe offers the same rapid and effortless acceleration, impressive interior, and command of the road without the sacrifice that comes with owning the standard M8 – a lack of interior space. In a sense, the M8 Gran Coupe sort of fixes everything that was wrong with the M8 coupe while bringing the M8 to a place where it’s more capable of carrying a family or – at the very least – four full-grown adults. Does the mean that the M8 Gran Coupe is just another four-door coupe or is there more substance to it? We spent a week with one to find out, and this is what we’ve learned.

BMW M8 Gran Coupe: Powertrain, Performance, Capability

2020 BMW M8 Gran Coupe Driven Drivetrain
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Under that menacingly long hood sits a hearty, life-giving 4.4-liter V-8 that pumps out a terrifyingly devilish 600 horsepower and 553 pound-feet of torque. This is the same engine available in the standard M8, and is also tuned to deliver up to 617 horsepower in M8 Competition models. In the growing performance-luxury segment the M8 Gran Coupe’s standard 600 horsepower has to do battle with the likes of the Audi RS7 and Mercedes-AMG GT 63 S, the latter of which is just a little more potent.

How Powerful is the BMW M8 Gran Coupe?

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In standard form the BMW M8 GC has 600 horsepower and 553 pound-feet of torque. These figures remain largely competitive with the Audi RS7 and AMG GT 63 S. The RS7 delivers a cool 591 horsepower and 590 pound-feet of torque while the heavier AMG GT63 S is good for 630 horsepower and 664 pound-feet of torque.

How Fast is the BMW M8 Gran Coupe?

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In standard form, the M8 Gran Coupe can hit 60 mph in 3.1 seconds on the way to a top speed of up to 190 mph when properly equipped. In comparison, the M8 GC’s main competitors – the Audi RS7 and AMG GT63 S can sprint to 60 mph in 3.5 and 3.1 seconds, respectively. The RS7 tops out at the same 190 mph when properly equipped, but in the long run the AMG GT63 S will win with a top speed of 196 mph.

BMW M8 Gran Coupe Fuel Economy

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The BMW M8 Gran Coupe is rated at 15 mpg in the city, 21 mpg on the highway, and 17 mpg combined. In comparison the Audi RS7 achieves 14 mpg in the city, 24 mpg on the highway, and 17 mpg combined. The AMG GT 63 S also matches the M8 GC’s 15 mpg city and 17 mpg combined rating but falls short on the highway at 20 mph. All three models managed the same combined fuel economy, but If you’re a highway warrior the RS7 will save you some money in the long run and the M8 will turn out to be a little more efficient than the GT63 S.

BMW M8 Grand Coupe – Interior Design and Amenities

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For a car that’s essentially designed to be at home on the track, you’ll be surprised to learn that it’s relatively happy – and will make you happy – on the street. It’s not exactly the most luxurious model in the segment, but that’s where the blend between luxury and performance comes together. The front seats are suitable for the luxury class while still providing enough adjustable support to keep you firmly planted during spirited driving. The rear seats, on the other hand could be a lot better. The fact that the rear seats are too upright and the padding at the bottom of the seatback all hint at the fact that the M8 was designed as a coupe first with the rear seats added as an afterthought.

The initial startup sequence of the M8 GC might have you thinking that it’s a loud car on the road (the initial growl is quite loud), but the M8 GC’s cabin is impressively quiet for its class. You would be hard pressed to identify any wind or road noise bleeding through into the cabin, and it’ll take some aging before any squeaks, creaks, or other trim noise rear their ugly heads.

Entering the M8 GC Can Be Troubling

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The BMW M8 GC looks amazing with its coupe-like roofline and rear-sitting cabin, but that cool look comes at a cost – ease of ingress and egress. You won’t find a whole lot of trouble getting into the front, but don’t be surprised if you ding your head the first few times as the roof is lower than you might expect. A full-size adult getting into the rear seats is mildly difficult, requiring a little bending and twisting to slide in without knocking your melon on the lowered roof. Once you’re inside, you’ll find that there does seem to be ample headroom, even in the back, so the lower roofline won’t be a problem once you get used to getting in and out.

Is the BMW M8’s Infotainment System Easy to Use?

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It’s not exactly a fault, so to speak, but the M8’s iDrive infotainment system isn’t the most intuitive out there. This is generally okay as the system has been around since 2001, has improved drastically over the years, and consumers simply upgrading to newer models will find themselves right at home. If you’ve never owned or driven a BMW for an extended period of time, you’ll find that the iDrive system does have a bit of a learning curve. Once you’ve played around a little, however, you’ll find that the system works well and won’t distract your while driving. It should also be noted that of the models it competes with from Audi and Mercedes, the M8 is the only model that still offers touchscreen and dial control.

Is the BMW M8 Gran Coupe Spacious Inside?

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As a large, four-door car, the M8 Gran Coupe does offer a fairly decent amount of interior space. It does suffer from a small lack of rear headroom, but it’s still inline with Audi’s RS7 Sportback and falls just shy of the AMG GT63 S. Front and rear legroom are also largely impressive, the latter of which is part of what contributes to such a low amount of available cargo room. It should be noted that BMW claims that the M8 Gran Coupe offers seating for five, but this is really a car designed to accommodate four people. A fifth person could fit in the middle of the rear seat, however, they’d have to straddle the extended center console – an uncomfortable feat for them and something that impedes on the comfort of other rear passengers.

BMW M8 Gran Coupe vs competition - interior room
BMW M8 Gran Coupe Audi RS7 Mercedes-AMG GT 63 S
Front Headroom 39.1 37 40.8
Front Shoulder Room 57.2 57.2 57.8
Front Leg Room 42.1 41.3 TBA
Rear Head Room 37.1 37.1 38.2
Rear Shoulder Room 54.6 55.9 57.2
Rear Leg Room 36.6 37 TBA

How Much Cargo Room Does the BMW M8 Gran Coupe Have?

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The BMW M8 Gran Coupe might excel in a lot of areas, but cargo room isn’t one of them. The rear cargo area of the M8 Gran Coupe can swallow up just 11 cubic-feet, putting it in dead last compared to the 12.7 cubic-feet available in the AMG GT63 S and the Audi RS7’s 18.9 cubic-feet.

BMW M8 Gran Coupe Exterior Design

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The M8 Gran Coupe shares some 90-percent of its DNA with its coupe sibling, with the biggest difference being the extra rear doors and the elongated roof. Looking straight on, it’s downright identical, and the same can be said for the rear. The two extra doors and the new roofline do give it more of an executive look, but the longer hood allows it to retain some of the sports car qualities you expect from something that wears an M badge and doesn’t sit nine inches off the ground. Overall, the M8 Gran Coupe is a very attractive car, and it’s certainly a viable option if you want something that looks sporty and professional at the same time while allowing the convenience of a usable rear seat.

How Big is the BMW M8 Gran Coupe?

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The BMW M8 Gran Coupe measures 200.9-inches long, 76.5-inches wide, and 55.9-inches high. It rides on a 119.2-inch wheelbase. When transitioning the M8 from coupe to gran coupe, it took more than just adding two doors, so it shouldn’t surprise you that the M8 Gran Coupe is quite a bit larger than the M8 Coupe. In fact, it’s 9.7-inches longer, 1.6-inches wider, 2.9-inches taller, and it’s wheelbase has grown by 8.1-inches.

Compared to the Audi RS7 Sportback, the Gran Coupe is longer overall and has a longer wheelbase, but it’s not quite as wide or tall, which translates to the RS7 having a little more interior space and easier ingress and egress.

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When looking at the AMG GT63 S, you’ll find that it, too, is wider and taller. It almost as long, though, and its wheelbase is only 3-inches shy of the M8 Gran Coupe.

All told, the M8 GC is a big car, so in terms of garaging, you’re going to need something pretty big. If you have a single-car garage, or even a two-car that is somewhat shallow, you might as well forget about it. You’ll definitely need some space to comfortably park the M8 GC in the protective cover of a secure garage.

How Much Does the BMW M8 Gran Coupe Weigh?

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The BMW M8 Gran Coupe tips the scales at 4,480 pounds, a figure that makes it lighter than both the Audi RS7 at 4,552 pounds and the AMG GT63 S with an estimated weight of 4,508 pounds.

BMW M8 Gran Coupe Competitors

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The BMW M8 is in the same category as cars like the Audi RS7 Sportback and AMG GT 4-Door Coupe. In fact, “Sportback” and “Gran Coupe” are just fancy way’s of saying 4-door coupe. Given the size and sporty nature of the M8 GC, however, the RS7 and GT 4-door are the primary competitors to consider, but there’s a catch because, pricewise, the M8 GC sits right between the two of them.

Is the BMW M8 Gran Coupe Better Than the Audi RS7 Sportback?

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Audi just released a revamped RS7 Sportback in 2020 and along with impressively sexy looks, the RS7 Sportback is more capable than ever. In terms of performance, though, don’t expect it to beat out the M8 in most situations. It falls just a little short in the horsepower department at 591 ponies (vs. 600 horsepower) but it does offer a bit more torque at 590 pound-feet (vs. 553 pound-feet). The RS7 is some 70 pounds heavier than the M8 GC, though, and it shows as it will take you 3.5 seconds to hit 60 mph. That’s 0.4-seconds slower than the M8. That said, if you’re in it for top speed, the RS7 will deliver as it tops out in standard guise at 174 mph vs. the Bimmer’s 155 mph. Both can be upgraded to max out at 190 mph, though, so in the end, you’ll still even out.

In terms of interior appointments, the RS7 won’t disappoint. It’s generally on par with the M8 GC in terms of interior space with exception of falling short in front headroom (by two inches.) It does offer a hair more legroom in the rear, and its 18.9 cubic-feet of cargo room bests the M8 GC and the other rival, the AMG GT63 S. Interior materials are exactly what you’d expect from Audi with plenty of leather and fancy trim. We prefer the Audi’s digital instrument cluster and infotainment system over BMW’s iDrive system but they are generally the same in terms of functionality, responsiveness, and ease of use. The Audi RS7 starts out at $114,000, which makes it some $16,000 cheaper than the M8 Gran Coupe as of December 2020.

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BMW M8 Gran Coupe vs Audi RS7
BMW M8 Gran Coupe Audi RS7
Engine 4.4-liter V-8 4.0 TFSI, V8
Transmission 8-speed Automatic quattro® 8-speed Tiptronic®
Horsepower 600 HP @ 6,000 rpm 591 HP @ 6000 RPM
Torque 553 LB-FT @ 1,800 – 5,600 rpm 590 LB-FT
Driveline AWD AWD
Fuel Gas Gas
Fuel Economy 15/21/17 14/24/17
Suspension Adaptive M Suspension Multi-Link
Steering electromechanical M Servotronic Rack-Pinion
Turning Circle 21.2 40
Front Tire Size 275/35ZR20 102Y P275/35YR21
Rear Tire Size 285/35ZR20 104Y P275/35YR21
0-60 MPH 3.1 seconds 3.5 seconds
Top Speed 155 mph (190 opt) 174 mph (190 opt)
Price $130,000 $114,000

Read our full review on the Audi RS7 Sportback

Is the BMW M8 Gran Coupe Better Than the Mercedes-AMG GT63 S 4-Door?

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The Mercedes-AMG GT63 S 4-door has been on the market since the 2019 model year, and while it does resemble a worked over CLS in more ways that we can count, it’s also a brutal machine that commands authority. To differentiate the 4-door from the CLS, AMG worked over the hood and fascias. In 63 S guise, the GT 4-Door is as equally aggressive as the M8 GC. In fact, if you swapped out the grilles and headlights, you might not be able to tell the two apart if you’re not in the know about both brands. Under the hood sits a beastly 4.0-liter V-8 that pumps out 630 horsepower and 664 pound-feet of torque – 30 ponies and 111 pound-feet more than the M8 Gran Coupe can muster on its best day. It’s also the only of the three we’ve discussed here that has a nine-speed transmission.

The AMG GT63 S isn’t all that much heavier than the M8 GC at 4,508 pounds (est), but that doesn’t help it in terms of acceleration. Just like the M8 GC it competes with, the GT63 S can hit the 60-mph sprint in just 3.1 seconds and will top out at an astounding 196 mph – 6 mph faster than the M8 even with the optional top speed update. It’s not quite as fuel efficient, but that’s not why you’re looking at the GT63, M8 GC, or RS7 anyway, now is it? Pricing for the AMG GT63 S 4 door starts out painfully at $161,200 and can come pretty close to the $200,000 mark if you’re not careful. Is it worth the extra $31,000 over the M8 GC? Well, it just might be if you like Mercedes.

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BMW M8 Gran Coupe vs Mercedes-AMG GT 63 S
BMW M8 Gran Coupe Mercedes-AMG GT 63 S
Engine 4.4-liter V-8 4.0-Liter V-8
Transmission 8-speed Automatic 9-speed auto
Horsepower 600 HP @ 6,000 rpm 630 @ 5500
Torque 553 LB-FT @ 1,800 – 5,600 rpm 664 LB-FT @ 2,500 - 4,500 RPM
Driveline AWD AWD
Fuel Gas Gas
Fuel Economy 15/21/17 15/20/17
Suspension Adaptive M Suspension Adaptive AMG Ride Control Multi-link
Steering electromechanical M Servotronic Rack-Pinion
Turning Circle 21.2 N/A
Front Tire Size 275/35ZR20 102Y P265/40ZR20
Rear Tire Size 285/35ZR20 104Y P295/35ZR20
0-60 MPH 3.1 seconds 3.1 seconds
Top Speed 155 mph (190 opt) 196 MPH
Price $130,000 $161,200

Read our full review on the Mercedes-AMG GT63 S 4-Door

Final Thoughts

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Overall the M8 GC is an attractive, fun-to-drive car with a functional rear seats and all the tech you’d expect from a BMW that sits firmly in the six-digit price range. For the most part, it’s well thought out and was clearly designed with the consumer in mind, but there are still areas – like cargo room and rear ingress and egress – that should be addressed when BMW decides to usher in a new generation. Of course, the M8 GC has essentially replaced the 6 GC, so there’s a possibility that this may be the only generation for the M8 GC. All of this in mind, if you need something that you can whip around curvy roads on the weekend but haul around the family during the week, the M8 Gran Coupe just might be for you. As long as you can afford to pay out at least $130,000, that is.

Philippe Daix
Obsessive and Compulsive Automotive Expert - phil@topspeed.com
Always on the lookout for the latest automotive news, Philippe Daix is our most senior editor and founder of TopSpeed.com. He likes to see himself as a consumer advocate with a mission to educate motorheads of all ages.  Read More
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