PORSCHE is taking its Panamera four-seat GT into a new dimension by fitting it with a plug-in hybrid drivetrain which produces an astonishing blend of power and economy.

On paper it's a car which can manage more than 90 to the gallon and accelerate from standstill to 60mph in less than 5.5 seconds.

In the real world such fuel figures are elusive but the Panamera S E-Hybrid shows incredible potential and an average close on 50mpg is realistic.

We managed to achieve 47mpg on an 80 mile run by making full use of the Panamera's clever power system which allows the batteries for the electric motor to be recharged on the move.

The car is fitted with three-litre V6 petrol engine mated to an electric motor which gives a combined power output of 416 horsepower - almost as much as the V8 engine used in the Panamera GTS,

As a hybrid it runs with the electric motor - mounted inside the eight speed auto gearbox - assisting the petrol engine and can be switched into EV mode working only on battery power for zero emission driving.

But being a plug-in it has larger capacity lithium-ion batteries and can be hooked up to the mains for external charging, a process which takes around four hours from a domestic supply.

What sets the Porsche system apart is the ability to recharge the batteries during the journey and to test it out we set off in electric mode on a full charge.

Porsche claims the S E-Hybrid can run for up to 22 miles on battery power with a top speed of 84mph making it very usable.

There is more than enough power from the electric motor to cope with general driving conditions and the car managed 16 miles before the battery was discharged and the V6 took over.

As well as a power meter on the dash there is also a battery charge gauge to supplement the traditional fuel display so you know what's going on and at the touch of a button recharge on the go was engaged.

It took 30 miles for the batteries to return to full capacity and then EV mode was reselected to give another 11 miles of zero emission driving.

Overall we had achieved 57 miles at normal speeds and for almost half the trip the petrol engine was not running. The average fuel readout on the trip computer showed 47.3mpg which was more than we achieved over a similar distance in a diesel engined Panamera which returned 36 to the gallon.

For a car weighing some two tonnes which can produce true sports car performance - top speed is 167mph - the results were nigh on incredible.

If required, the S E-Hybrid can also be switched into sports mode for pure Porsche-style driving and in every way the technology in this car makes it one on its own.

Because of the official 91.1mpg for the S E-Hybrid emissions are rated at 71g/km which makes it exempt from the London congestion charge and for business users it equates to a benefit in kind banding of just five per cent.

Most of the recharging functions can be controlled remotely from a smarthphone and the charging cable comes with an adaptor which allows it to be connected to all types of sockets.

The plug-in hybrid costs from £88,967 which places it mid-range in the restyled Panamera line up which now runs from £62,922 for a three-litre diesel to £107,903 for the 4.8-litre twin turbo V8.

Given its tax advantages and that this is an electric vehicle which is not constrained by range the plush new Panamera plug-in is the only car on the market at the moment which embraces the latest technology in such dynamic fashion.