Overall rating:

Electrically powered cars might be in their infancy, but the instantaneous torque and near silent running fit rather comfortably with Roll-Royce's quest for dignified, hushed performance. Rolls-Royce has replaced the regular Phantom's 6.75-litre V12 and six-speed transmission with 96 batteries and two electric motors. The result is very Rolls-Royce, but it remains an experimental prototype vehicle for now.

Key Facts

Pricing: pick a number
Engine: two electric motors
Transmission: automatic, rear-wheel drive
Body style: four-door luxury saloon
Rivals: 20 Nissan LEAFs, Fisker Karma, a regular Phantom and lots of carbon offset buying
CO₂ emissions: 0g/km
Range: 100 - 120 miles
Top speed: 99mph
0-62mph: 'under eight seconds'
Power: 388bhp
Torque: 590lb.ft

In the Metal:

It's a Rolls-Royce Phantom, which means all its imposing gravitas, but with a few subtle identifiers to mark it out as something a bit different. The Spirit of Ecstasy is lit by blue LED light and its usual stainless steel construction has been replaced by an opaque material called Makrolon. There are more LEDs around the rear filler cap, which, unsurprisingly, has been replaced by a plug socket.

A special fine metallic paint, requiring 16 different applications, gives the 102EX a particularly deep lustred finish. Inside, it's all the same, which means ankle deep carpet, fine wood and chrome finishes befitting of a car that costs so much.

Driving it:

It might feature an entirely bespoke, experimental powertrain but the 102EX feels little different to its conventionally powered Phantom relatives. The start-up is silent so the only means of knowing the 102EX is ready to roll is via the instrumentation. Push the accelerator to the floor and the weighty luxury machine will reach 62mph in around eight seconds and reach its 99mph governed maximum shortly afterwards.

That's uncouth, and extremely detrimental to the potential range of the battery-powered drivetrain. Drive it more sedately and Rolls-Royce reckons it'll manage anything between 100- and 120 miles - enough for a hop from office to heliport. At more sedate town speeds it's as hushed and effortless as its 6.75-litre V12 petrol relative. Two electric motors provide the same seemingly limitless linear surge, the response to demands from your right foot metered out swiftly and silently. That ease and refinement are particularly suited to the Phantom's stately appeal and huge comfort.

In every other way the 102EX is pure Rolls-Royce: the thin-rimmed steering wheel nicely weighted and accurate, the suspension gliding over imperfections in the road. It really does feel like a regular Phantom, which highlights not just the success of integration of the experimental electric drivetrain, but the deeply impressive performance and refinement on offer from the conventional car.

What you get for your Money:

Even the wealthiest Rolls-Royce owner might find the cost of the experimental electrically driven Phantom a bit expensive. Not least as the 102EX started out as a regular Phantom, before it had its engine and transmission removed and replaced by its battery and electric motor combination. You can ask Rolls-Royce to build you one, but we suspect the answer will be a polite no - however deep your pockets are. It's irrelevant then, but figure on a cost in the region of £600,000 - £700,000.

Worth Noting

Rolls-Royce's engineers admit that the actual installation of the electric motors and batteries was a relatively painless process. What has taken development time is the details; getting the instruments to work, re-engineering the power steering and suchlike.

Successful as it is Rolls-Royce's engineers talk excitedly of other potential drivetrain solutions, with one suggesting a gas turbine generator system to overcome the range issues with the conventionally charged batteries. Rolls-Royce is also looking at induction charging systems, where no physical connection is required to top up the batteries.

Summary

As experimental vehicles go the Rolls-Royce 102EX is hugely successful in mating future-looking technology to an existing platform. The electric drivetrain suits the Phantom particularly well, its effortlessness and silence fitting with Rolls-Royce's high luxury, performance and refinement expectations. Like all electric vehicles range limitations and charging times curtail its ultimate usefulness, but as battery and charging technology advance apace a fully electric Phantom may be a production reality sooner than you'd think.