The S580e's ability to set off in complete silence and travel for truly extended distances on its electric motor alone is impressive. With 148bhp from the electric motor, it isn't exactly rapid in Electric mode but the presence of 325lb ft of torque the moment you nudge the throttle provides sprightly step-off and near-to-silent cruising at up to 87mph.
The key to the 64-mile WLTP electric range is a 28.6kWh lithium ion battery under the boot floor. For comparison, the Audi A8 60 TFSIe quattro can manage only 29 miles and BMW 745Le xDrive 36 miles.
Even more impressive is the performance when the two power sources are combined. With a system output of 503bhp and 553lb ft, there is crisp response and huge flexibility in Hybrid mode out on the open road. It is quite quick, too, sprinting effortlessly to three-figure speeds and beyond on German autobahns.
All this and claimed consumption of 217.3-353.1mpg as well as average CO2 emissions of 18-30g/km on the WLTP cycle, thanks in part to a coasting function and a very effective brake energy regeneration system.
The potency extends to charging. The new plug-in hybrid S-Class comes with a 3.7kW AC charger as standard but also supports charging on both an optional 11kW AC system and 60kW DC system - the latter of which is claimed to provide it with a 10-80% charge inside 30 minutes.
It's not all rosy, though. The gearbox isn't always silken, the brake pedal lacks precision and the battery's extra weight makes this the least dynamically adept new S-Class we've driven.
Still, it's refined, potent, smooth and very impressive.