Because the Mercedes has such a refined and composed nature, it comes as somewhat as a surprise when you first hear the diesel engine fire into life.
It's not excessively noisy, even when worked hard, but it lacks the outright mechanical refinement of the six-cylinder diesel offered elsewhere in the range; it's not uncommon to feel a slight vibration through the steering column either.
By no means is it disappointing but it feels at odds with the Mercedes' luxury nature and takes the edge off that 'magic carpet' experience that you might otherwise expect.
The hybrid powertrain does function well, however. The diesel engine cuts in and out quickly and effectively and the electric motor grants the S-class silent low-speed cruising and coasting. The seven-speed transmission is equally competent, shifting through its ratios quietly and unobtrusively.
Charge from the hybrid's battery can be depleted quickly – even when parked, no doubt due to the Mercedes' substantial electrical and ancillary system – but it also replenishes at a sensible rate, meaning there's usually something in store when you need it.
There is, it must also be said, also something immensely satisfying about rolling along in absolute silence in electric mode – a feel-good factor that's enhanced by the fact that the S-class is capable of accelerating in a comparatively swift and eager fashion if needed.
During testing the car returned an indicated 34mpg, which while some way off the claimed average was good given the conditions – and still quite remarkable when considering the S-class' kerb weight.
At that rate of consumption a full tank of fuel would last for some 520 miles; average the claimed economy and the S-class will cover around 940 miles. Few, as a result, should have any range-related issues.
Otherwise, the usual Mercedes S-class qualities remain. It's easy to drive, supremely comfortable, lavishly equipped, impeccably well built and finished to a class-leading standard.
It may not be the most engaging luxury saloon available, but as a means of transport – even more so as a passenger – it's hard to beat.