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Somewhere around the late 1990s, automakers began experimenting with turning the sounds of their engines into signature elements of their brands. Audi and Volvo five-cylinder engines were noted for their signature warbling sound. The Subaru WRX's signature boxer-engine rumble became easy to recognize. At the same time, the Nissan 350Z's VQ V6 had a distinctive tonal howl that gave it away. The Ferrari 355 F1 became one of the first production cars with a bypass valve in the muffler that could open up additional breathing for its high-RPM wail. Right around the same time, Mercedes-Benz was selling V8-powered German muscle cars to American shoppers who loved a good V8 soundtrack.
Turning Sound Into A Brand Signature
In the muscle car era, almost everything on the road had a big noisy V8. Gas was cheap, horsepower was easy to build, and engines could shoot harmful pollution into the atmosphere. The emissions era squashed all of this, quickly suffocating the mighty V8 with catalytic converters, new emissions hardware, and ultimately de‑tuning once‑potent engines into lazy, wheezing couch potatoes.
It would take a few decades of advances, but the industry would eventually shift to wave after wave of modern engines that brought power levels back up while meeting the latest emissions targets. Many of the advances made while downsizing performance engines in the '80s and '90s centered around computer‑aided design and enhancing engine breathing characteristics.
Along the way, development of new cylinder heads, exhaust systems, valve‑timing systems, and intake hardware gave engineers experience that would make them masters of air and exhaust‑gas flow before long. Some of the most glorious‑sounding engines of the '80s and early '90s were still just the accidental result of performance engineering of the day rather than intentionally designed.
This was an exciting era to be a car enthusiast. New performance engines of all cylinder counts arrived with new performance technologies, and the sound of these new engines was an increasingly prominent part of the experience.
Add another decade’s worth of evolution to engine electronics, computer‑design power, and rapid parts prototyping, and we wind up around 2010, at the peak of automotive sonic engineering with machines like the Lexus LFA (2011) and its 4.8‑liter V10 (553 hp, 354 lb‑ft) literally tuned like a musical instrument by Yamaha.
If you didn’t have Lexus LFA money, there was also the IS‑F (2008–2014), with a 5.0‑liter V8 (416 hp, 371 lb‑ft) that could project its intake‑tract snarl into the cabin on command via a special duct. A few more years would see the arrival of the Jaguar F‑Type (2014 launch), with its 5.0‑liter supercharged V8 (up to 575 hp, 516 lb‑ft) and a crafted exhaust note intended to be as defining an emotional element as its styling.
Multi‑mode exhaust systems were catching on in a serious way, making their way into Camaros (2016+ SS) and Mustangs (2018+ GT) and Boxsters / Caymans (2013+ with Porsche Sport Exhaust). Not before the Porsche 911 first offered Porsche Sport Exhaust (PSE) in 1999, years before subsequent systems were widely rolled out across the model range.
AMG Understood The Mission
When AMG switched to the supercharged 5.5‑liter M113K V8, with 469 hp to 493 hp and 516 lb-ft to 531 lb‑ft in the early 2000s, its approach gave rocket‑sedan shoppers a high‑torque alternative to the hot new BMW E39 M5 of the day, as well as a unique take on the German performance‑sedan soundtrack with a meaty exhaust note and that extra supercharged ‘zing’ if you were listening carefully. A generation later, AMG released its 6.2‑liter M156 V8, making from 451 hp to 518 hp and 443 lb-ft to 465 lb‑ft, to replace that era of supercharged engines with a new wave of big‑displacement power, and a new soundtrack was along for the ride.
When it launched in the 2008 C63 AMG, Canadian journalists tested some of the first units on our shores at a track event, and your writer was in attendance. I have fond memories of the sound of these first C63 AMGs making my most well‑mannered colleagues swear quite vigorously. Almost nothing on the road with a warranty sounded as ferocious at the time, and many concluded that AMG really got exhaust tuning in this era.
Still, the AMG V8 was in a constant state of evolution, and a new version would come along soon with some big tailpipes to fill, and some big challenges for engineers seeking to deliver the ultimate AMG soundtrack, which incoming regulations were threatening to silence.
Engines And Their Soundtracks Were Being Forced To Downsize
The M156 was the last naturally‑aspirated AMG V8 engine before a virtually industry‑wide shift to downsized, turbocharged engines was required to meet incoming emissions and fuel‑economy regulations. The great big 6.2‑liter unit would be retired and replaced by a sequence of downsized turbo V8s. The first was the 5.5‑liter M157 (518–577 hp, 516–590 lb‑ft), and later the 4.0‑liter M177/M178 (469–603 hp, 479–627 lb‑ft), complete with the latest hot‑vee design.
Those engineering challenges we mentioned? First, turbocharging a V8 engine can mess up its sound. The signature throbbing exhaust pulsations of a cross‑plane V8 are a key ingredient in its soundtrack, but twin‑turbo V8 engines route those pulsations directly through a turbine. The turbine steals some of their energy to drive the compressor, and in the process it smooths, quiets, and attenuates the very pulses that make a V8 sound like a V8.
For the turbocharged V8 engines to come, engineers would need to craft a signature V8 sound without access to the raw pulsations that once defined it. The increasing rollout of turbochargers tended to muffle the soundtracks of the engines they were applied to, and luxury automakers were also making great strides in NVH, meaning car interiors were better insulated against outside sounds than ever. Complicating matters, additional noise regulations meant that the maximum permissible volume at a vehicle’s tailpipes was about to start dropping.
Enthusiasts had fallen in love with that AMG V8 soundtrack, but the industry was pushing towards, and even mandating, quieter cars. As reported by Carsales.com in 2019, European legislation was coming for the once loud‑and‑proud soundtracks of performance models, and Mercedes said it didn’t make sense to engineer different exhaust systems for multiple markets. AMG’s hot‑rods could no longer emit enough tailpipe noise to satisfy what enthusiasts expected when they put their foot down, so the sound had to come from somewhere else.
At that time, they switched from a standard that had been in effect for almost 30 years to a completely revised guideline that turned the previously valid test procedure and catalog of requirements upside down… the static limit was replaced, and a phase model was introduced, which came into force in 2020. In two‑ or four‑year stages, the noise limits now continue to fall. For us, that means adjusting vehicles regularly.
- Jörg Blaeß, an acoustic engineer with AMG
That’s the backdrop that shaped the twin-turbo V8 era, and specifically a moment when AMG had to reinvent how a modern V8 should sound under the tightest noise constraints the engineers had ever worked with.
The AMG Soundtrack In The Turbo Era
Various solutions were applied across different engines and model lines to ensure drivers got the auditory experience they expected. Along the way, engineering implements and features blurred the lines between synthetic engine sounds and enhanced real engine sounds. There were several ways to enhance engine sounds, ranging from bypass valves within the mufflers to carefully shaped manifolds to special sound processing systems like AMG Real Performance Sound, which blurred the lines between them.
According to Mercedes-Benz, things started with variable exhaust flaps, which got a foothold in the Mercedes A-Class AMG model range from 2013. In that application, the variable exhaust system could be used to deliver a higher-quality sound with improvements to both performance and cabin noise levels from a four-cylinder powerplant.
Next came electric cars, which didn’t have engine sounds, but had drivers keen on hearing something exciting when they put their foot down. For Mercedes and AMG electric products, a synthetic sound system was developed to pump in artificial propulsion sound effects through the vehicle’s speakers. Competitor BMW was doing similar work on combustion-powered performance flagships to augment exhaust notes flattened by turbocharging. This gave a lot of enthusiasts very strong feelings.
Eventually, enhanced exhaust systems and artificial engine sounds came together in yet another system called the AMG ‘Real Performance Sound’ system, which rolled out in 2019 with the Mercedes-AMG A 45 S 4MATIC+. With it, a pressure sensor was installed into the exhaust system to measure the physical characteristics of the exhaust flow in real time. The signal gathered by the pressure sensor is enhanced by a processing computer, with unwanted sounds reduced and desirable sounds amplified and pumped back into the cabin. It’s an up-rendered take on the engine’s actual sound, making it real to some, fake to others, and somewhere in between for others still.
The original C63 AMG with 6.2-liter V8 engine had a static, fixed exhaust system and its famous sound as created entirely by manipulating plumbing, muffler packaging, and some engine control parameters during development. By 2015, the C63 got its next engine: the downsized four-liter hot-vee twin-turbo V8. Now, the fixed exhaust system was replaced with an optional performance exhaust that concealed the development of the variable exhaust flap hardware originally introduced in the Mercedes-Benz A 45 AMG. For the Mercedes-AMG C 63 with 4-liter twin-turbo V8, the number of flaps was tripled for a broader, higher-quality sound spectrum.
From the driver’s seat, the new engine lacked the harsh, raw sharpness of the naturally aspirated V8 before it, but extensive development work on the manifolds and mufflers, along with the variable exhaust system, strategically manipulated volume and pressure for a similarly thrilling effect. It was a slightly softer, more refined take on the original anger behind its predecessor’s soundtrack, with a surprising amount of V8 burble maintained, no pressure sensor required.
Today, you can find AMG Real Performance Sound in cars like the New Mercedes-AMG GLC 53 4MATIC+. In it, Mercedes says a new exhaust system with special mufflers maintains the “characteristic crackling on throttle lift-off and deep exhaust note during dynamic acceleration”, and that the AMG Real Performance Sound System, working in conjunction with a selectable exhaust system “enables customers to tailor the sound of the engine further.”
This technology has also made its way into the brand's 4.0-liter V8 flagships these days, like the new GT 63 Coupé and S 63 E Performance. To preserve their legendary soundtracks in the modern era of tightening noise laws and ever-quieter car interiors, the job of a modern AMG acoustical engineer is no longer just about tuning an instrument, but also deciding exactly how to mic the stage.
Sources: Mercedes-AMG
