The big news, though, is the appearance of a new twin-turbocharged 4.0-litre V8 engine based on the more heavily tuned unit used in the Mercedes-AMG S63. This new engine replaces the old twin-turbocharged 4.7-litre V8 from the outgoing S500. Its additional 13bhp takes power up to 462bhp, while torque is the same at 516lb ft.
With a pair of twin-scroll turbochargers operating centrally within the space between the cylinder banks, thus requiring shorter induction paths than those of its predecessor, the new engine has not only better low-end response but also greater mid-range flexibility and a sturdier top end.
The power delivery is very linear, extending to the 6200rpm redline in one wonderfully muscular surge on a loaded throttle. With Sport mode engaged, at which a series of flaps open to increase the volume of the exhaust system, it’s also terrifically melodious.
Switch into Comfort mode to trigger a more conservative set of software maps and the new V8 is wonderfully refined and satisfyingly reserved in nature. On light throttle loads, a cylinder deactivation function seamlessly closes down four cylinders to improve fuel economy.
The standard nine-speed torque converter automatic gearbox also appears to have taken a step forward. In automatic mode, it's ultra keen to shift up to ensure the best possible economy and lowest emissions, and the shifts feel crisper and softer than before.
With Mercedes-Benz’s three-chamber Air Body Control suspension as standard, the S560 has a wonderfully compliant and controlled ride.
The electro-mechanical steering is very light and bereft of much feedback at the straight-ahead, although it gains heft and feel as you apply lock.
On more demanding roads, the S560 is surprisingly proficient, with nicely progressive and well-controlled body movements that belie the car's considerable size. The S650 turns in keenly, and with Mercedes-Benz’s 4Matic system doling out drive to each wheel, there's sufficient grip and excellent traction to keep things tidy when you start to push. The car's most compelling traits, though, are evident at a constant cruise, where superb refinement and excellent ride quality provide it with outstanding long-distance properties.