Road Test: Porsche Panamera 3.0 V6 S E-Hybrid 4dr Tiptronic S

Green. Day-Glo green specifically. Porsche is so enthused by the Panamera S E-Hybrid's environmental credentials, it's broken out the highlighter pen and gone at the badges and brake calipers with schoolboy-customising enthusiasm. So, the German company has added plug-in functionality to its sport saloon/battery car mash-up, updating the Panamera S Hybrid to create the S E-Hybrid.

New styling and revised lights across the Panamera range present a less wince-inducing face and tidier rump to the world. A crease at the bottom of the flanks helps neaten things up a bit, but the Panamera remains striking rather than beautiful.

With 91mpg and 71 g/km of CO2, the E-Hybrid is freakishly green for its size and performance. Yet this unlikeliest of planet friends can reach 62mph in 5.5 seconds and boasts a top speed of 168mph.

The plug is only part of the reason, as Porsche also fits lithium-ion batteries, not the nickel-metal hydride items of its predecessor. The electric part of the drivetrain has more than doubled in output from 46bhp to 94 (those lithium-ion batteries offer five times the energy capacity of the old ones).

Plug into a domestic three-pin outlet, and they'll charge in under four hours, giving you a theoretical everyday range of between 11 and 22 miles on battery power alone - at speeds of up to 84mph. Yes, really. It defaults to silent electric-only mode on start-up, too - so it's neither noxious nor obnoxious.

Three buttons inside control the driving modes - Hybrid, E-Mode, E-Charge and Sport - while the instruments attempt to tell you what the powertrain is doing. In Hybrid, it'll exploit its electric drive at any opportunity, coasting at speed and only demanding conventional power when it's absolutely necessary. E-Mode adds an artificial step to the accelerator to encourage light-footedness. But even so, it's surprisingly brisk when running on battery power.

Pop it into E-Charge, and it'll scavenge back any power it can to charge up the battery for future E-Power use, the whole system working with a slickness that's genuinely impressive. And, the 3.0-litre supercharged petrol engine kicks in quickly regardless of mode.

Downsides include its additional bulk and the slightly detrimental effect it has on the Panamera's agility, and the brake pedal, which feels not dissimilar to one that's been punished on a race track - it's soft and long, but not very strong. The gearbox too, an 8spd auto here, can sometimes get a bit flummoxed. Otherwise it's a regular Panamera, which is to say quick and composed. It all comes down to the numbers then. But if you're a London-based high-flyer wishing to avoid the C-Charge and pay a tiny tax bill, then the Panamera S E-Hybrid could be just the thing. Otherwise, do the riotous rather than righteous thing and buy a GTS or Turbo.