Mercedes-Benz's AMG performance division used to be synonymous with big-inch V-8 naturally-aspirated performance, with Affalterbach's marvelous 6.2-liter V-8 being one of our favorites. The 5.5-liter biturbo V-8 has largely displaced the 6.2 in the AMG lineup, but the performance sub-brand's V-8 offerings are about to get downsized further, according to AutoExpress. The first vehicle to receive the rumored 4.0-liter twin-turbo V-8 is the 2015 C63 AMG.
The German brands have long since abandoned the practice of decklid numerology being a literal description of engine displacement, and although the C63 appellation will probably continue, it will be applied to a significantly smaller engine. AutoExpress estimates the output of the downsized AMG bent-eight to be between 450 to 500 horsepower with the available Performance Pack.
In terms of specifics on the new engine, AMG product chief Tobias Moers only coyly said, "You are now familiar with our 2.0-liter four-cylinder engine? Well, you can imagine what happens when you put two of those together." Reading between-the-lines, the new AMG V-8 could have a flat-plane crank, which makes for optimal exhaust-pulse phasing for turbochargers, but results in a flat exhaust note that sounds similar to a four-cylinder. AMG V-8s, including the recent 5.5-liter twin-turbo, have always had a burbly exhaust note that comes with a cross-plane crank. But if such a configuration makes for optimal performance, we could learn to love the new sound of AMG performance.