Mercedes-AMG C63 S Coupe v BMW M4 Competition video review
It's the latest round in the German grudge match between these heavyweight performance coupes.

Value

BMW: The M4 was already generously equipped with surround view cameras, adaptive bi-Xenon headlights, dual-zone aircon, keyless entry and ignition, leather M Sports seats, 16-speaker Harman Kardon sound system, digital radio and navigation. The Competition upgrades include blacked-out grille, side vents, window surrounds and exhaust plus new look 20-inch alloy wheels (up from the standard M4's 19s). Cheaper than the C63 but still well specced enough to give it a slight edge in this department.

Mercedes: The AMG is $7785 more expensive than the M4 but matches it for all the key specifications and gets some extras. Standard gears includes surround view cameras, 13-speaker Burmester sound system, digital radio, navigation, TV tuner, AMG specific head-up display and 19-inch front alloys and 20-inch rears. Plus it gets a bigger, more powerful engine to offset its extra cost.

Winner: BMW

Inside

Head-to-head: BMW M4 Competition v Mercedes-AMG C63 S Coupe. Photo: Lucas Kennedy

BMW: While largely the same as the standard M4 the Competition gets some small but important changes to set the cabin apart. There are new M Sports seats for the front occupants, with cut outs in the backrest and integrated headrests with an illuminated M logo in-built for a modern take on the sports bucket. The seat belts even get the traditional M division tri-colour piping.

There's still the same mix of leather and carbon fibre from the 'regular' M4 to give it the right balance between sportiness and luxury.

Mercedes: The AMG has the same blend of sports and luxury as the M4, albeit with a very different style. Whereas the BMW has a more contemporary design, with more straight lines, the Mercedes features retro-style round air-con vents and dark wood veneer finishes. But both feature all the same modern conveniences - large, tablet-style display screens atop the console and relatively straight-forward rotary dial interfaces. The AMG gets the slight edge thanks to its more comfortable seats and better use of space; the steering column-mounted gearshift frees up more space in the centre console.

Winner: Mercedes

Engine

BMW: Some of the biggest changes for the Competition package are under the bonnet. The 3.0-litre straight-six has been retuned and there is an enhanced sports exhaust system. As a result power is increased to 331kW (a 14kW bump) but torque remains the same at 550Nm.

Paired with the seven-speed dual-clutch transmission the M4 Competition cuts 0.1-seconds off its 0-100km/h sprint, to an even 4.0-seconds. It feels that fast, with excellent mid-range punch that allows the BMW to build speed at a very rapid rate.

Unfortunately it isn't matched by a suitable soundtrack. BMW was famous for building sweet sounding inline six-cylinder engines but this new turbocharged version sounds artificial; more synthetic than mechanical.

Mercedes: The new C63 Coupe ditches the previous model's 6.2-litre naturally-aspirated V8 in favour of a downsized twin-turbo 4.0-litre V8. Not surprisingly the bigger engine comfortably out-guns the M4, with 375kW and a whopping 700Nm.

AMG has managed to tune most of the turbo lag out of the car so the throttle response is almost as instantaneous as the old V8. And the response is nothing short of ferocious. With so much torque the rear tyres can struggle for traction at times but once they grip up the C63 is super quick, pulling strongly across the rev range.

To cap its dominance over the BMW engine the AMG V8 is one of the best sounding units on sale today - with a deep growl that gives the C63 an imposing road presence.

Winner: Mercedes

How it drives

BMW: The biggest changes for the Competition are to the chassis and suspension. There are new shock absorbers, springs, anti-roll bars and bushes plus the limited-slip differential and the stability control system has been reworked. Those changes make the M4 even sharper on the limit but, as with the standard coupe, the car remains less-than-compelling to drive.

Finding the sweet spot in the M4's handling is difficult as the handling, especially the steering, can be on or off like a lightswitch. Once you find it though the M4 Competition is an incredibly agile and responsive coupe.

However, the stiffer suspension makes it a hard car to live with on Australian roads, even in the 'Comfort' setting of the selectable drive modes. It feels like it is transmitting most bumps through the cabin, crashing hard over the bigger dips in the surface.

Mercedes: The C63 is notably softer and more compliant compared to the M4 Competition, but that doesn't make it any less engaging to drive. In fact, it has the opposite effect, making the C63 a nicer car to be in across a broader range of conditions.

Using the selectable drive modes changes the character of the car even more noticeably than the M4. Whereas the BMW always feels sporty and stiff, the AMG in comfort mode actually feels comfortable. But wind it up to 'Sport' or 'Sport+' and it becomes a proper sports coupe, with a more aggressive engine response and firmer, more responsive ride.

The AMG also feels more progressive than the BMW, making it an easier car to drive at the limit.

Winner: Mercedes

Kerb appeal

BMW: The M4 was already an impressive looking coupe, with a much more muscular appearance to the regular 4-Series range. The cosmetic changes to the Competition set it apart from the standard M4, with the unique wheels and blacked out exterior trim.

Mercedes: The C63 also projects a muscular appearance, albeit with Mercedes' now trademark softer, swooping lines (particularly around the rear three-quarter). But the dark alloy wheels, deep grille, wide body and angry soundtrack make the C63 standout in traffic more than the BMW.

Winner: Mercedes

Verdict

BMW: The M4 Competition is a better car than the regular M4, making it faster and more responsive. But it doesn't fix the on-off nature of the engine and the ride remains too track-focused.

Mercedes: Despite the major changes under the bonnet the new C63 Coupe retains the same core attributes that made the old model such a success. The new turbocharged V8 is a gem and the AMG engineers have found the right balance between dynamic handling and liveability.

Winner: Mercedes