Owners revere the M156 as AMG's first engine designed in-house 'from the oil pan up,' a big naturally aspirated 6.2 that makes huge low-end torque yet spins to a 7,200-rpm redline. Because stock output is only about 80hp per liter, commenters argue the internals are lightly stressed and high mileage is no concern if the car was maintained, contrasting it with high-revving exotics that stress their internals far harder.
The 6.2L naturally aspirated M156 V8 character
Mercedes-Benz CLK63 AMG Black Series (C209) · mechanical