The dual-wall stainless steel exhaust system is obviously tuned to produce a pleasing V8 rumble, but interestingly its configuration is the primary reason for horsepower differences between the various vehicles in which the new V8 is placed. In the CLK63 AMG Coupe and Cabriolet, for example, the engine makes 481 bhp at 6800 rpm. With more room under the chassis for the exhaust system, the ML63 AMG sport utility vehicle makes 510 bhp at 6800 rpm from the same engine. These numbers are outstanding, among the highest horsepower per unit of displacement of any naturally aspirated engine. AMG's new V8 also continues with the Affalterbach tradition of "one man, one engine" as each engine is completely assembled by one technician. Unfortunately, AMG has chosen to hide all of this sophistication, high technology, and craftsmanship under a tacky and flimsy plastic cover that sits atop and obscures the engine.
Back to whyNone of which actually answers the question why AMG would bother to build an all-new engine. The new 6.2-liter V8 doesn't share any parts with any other Mercedes-Benz engine family. It has a different cylinder bore than any other V8 in the Daimler-Chrysler lineup, meaning that it has to be produced on its own dedicated assembly line. The displacement of the engine is at the limits of what the block can handle, which means unless AMG resorts to supercharging or turbocharging, the engine is already near its power limit for street applications, especially with the rpm limits set by the automatic transmission.
The idea of an all-AMG designed and built engine does seem important to Europeans. This may be more important to buyers there than it is to AMG fans in the U.S.; most customers here are happy just to be able to finally get hot-rod Mercedes-Benz products. The perception in Europe is that an AMG should compete with an Aston Martin or a Porsche, not that it is simply one of the options customers have when they walk into a Mercedes-Benz dealership.
Another justification for an all-new engine from AMG might come from the company's racing heritage. If the bore of the new engine was reduced to 92mm, it would fall into the 5.0-liter category for racing and make an almost square (bore and stroke equal) engine where lighter pistons would be capable of even higher revolutions. Admittedly, 92mm would be a smaller bore than the 100mm that Herr Ramler prefers for a racing engine, but it is certainly conceivable. Another possibility that several of the AMG engineers talked about, but insisted was just an idle musing, was a 180-degree flat-crankshaft with a shorter stroke. Apparently, this too would bring the displacement near to five liters.
Who cares?Ultimately, perhaps it doesn't matter why AMG has spent so many of its resources to build its own engine. Its power and performance are impressive, regardless of the vehicle in which it's placed. With 369 lb-ft of torque available at 2000 rpm, rising to a total of 465 lb-ft at 5200 rpm, the engine pulls even the heavy ML63 AMG from zero to 62 mph in five seconds and to an electronically limited top speed of 155 mph. Does anyone actually need a sport utility vehicle that is this fast? And if so, why? The ML63 felt big and bulky on the narrow roads around Granada, Spain, but the heavy SUV had no trouble passing locals in their SEAT sedans, even uphill.
On the other hand, fast cars are a one of life's true pleasures, and the CLK63 AMG Coupe will sprint to 62 mph in 4.6 seconds and sounds like a Camaro on steroids in the process. Stiffly sprung and directly connected to the pavement, the CLK63 AMG feels like exactly what it is: a factory hot rod. Unfortunately, the coupe isn't on the menu for U.S. buyers (write to Mercedes and explain why we deserve it), and we will only get the CLK63 AMG Cabriolet, which takes an additional agonizing 0.1 seconds to reach 62 mph (in 4.7 seconds), but has commendably little cowl shake despite its open-air ambiance.
AMG has always been about engines, and that in itself is reason enough to build its own for the first time in the company's history. AMG certainly has done a first rate job. If a modified version of this engine shows up in a racing car in the not- too-distant future, the real reason for its existence will suddenly become abundantly clear.