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.
Should I buy one?
Mercedes' hybrid S-class offers up impressive – and potentially attainable – economy figures but its four-cylinder diesel engine is not refined enough for a car of its calibre.
If the Mercedes instead had a six- or eight-cylinder diesel then it would deliver the blend of performance, economy and mechanical refinement that you might hope for.
Those seeking a comparatively frugal S-class should instead opt for the diesel S 350 BlueTEC. The smoothness of its V6 is much better suited to the car and it's still claimed to average a more-than-tolerable 50.4mpg. You may even find it as economical as the hybrid, depending on your usage.
Alternatively, if the unique abilities of a hybrid system appeal, you could buy for the similarly priced S 400 Hybrid L. It couples a serene petrol V6 with the same hybrid system, maintaining the S-class's tranquil luxury with ease.
Mercedes-Benz S 300 BlueTEC Hybrid L AMG Line
Price £72,260; 0-62mph 7.6sec; Top speed 149mph; Economy 61.4mpg; CO2 120g/km; Kerb weight 2035kg; Engine 4 cyls, 2143cc, turbocharged diesel, plus electric motor; Power 201bhp at 3800rpm, 27bhp electric; Torque 367lb ft at 1600-1800rpm, 192lb ft electric; Gearbox seven-speed automatic