MERCEDES-BENZ is working as hard as any major car maker towards a totally electric future - but it hasn't arrived quite yet.

The billions of euros being poured into providing battery-only personal mobility will have us all plugging our new cars into the mains to make them move.

Until then, we have choices to make and here is one of the latest - and perhaps most sensibly practical - for the driver with a family to support and generous income to help do it.

For the new Mercedes-Benz E 300 de mixes a diesel engine with an electric motor and battery to make the longest of journeys an economical drive and shorter ones so inexpensive you may need to check your sums.

Taking the short before the long; if your trip is less than about 31 miles (and statistically, most of them are) you can do the whole lot on battery power for mere pence.

It can be charged, via a neat plug beneath a rear light cluster, in around five hours from a standard UK three-pin domestic socket (in the garage overnight, perhaps) or from a 7.2kW charger in 1.25 hours.

You can tell your car to use electric power only, or diesel only, or to charge up the battery or - probably the go-to option - tell the car to uses its clever electric brain and make up its own mind.

The result is an official fuel consumption of up to an astonishing - and frankly unobtainable - 176.6mpg, even using the tough new regime that's supposed to make these figures more real world realistic.

But, and this is where the diesel part of the hybrid equation kicks in, when the battery's range is exhausted the car becomes a still frugal diesel, and one where a business user will smile at the thought of the car's 41g/km emissions rating and consequent BIK tax rate of just 13 per cent.

Nearly all hybrids use petrol and become much thirstier and more taxingly inefficient as a result. It would be a rare day when your diesel/electric E-Class failed to provide better than 50mpg on even the longest journey.

Having found the £47,700 needed for an SE spec version of the new E 300 de or £50,195 for an AMG Line model, an owner is not going to feel shortchanged on the performance front, even with a diesel doing much of the work.

A combined output of 302bhp and 700Nm of pulling power from the 2.0 litre four-cylinder diesel engine and electric motor working together mean this big and roomy saloon will touch an electronically limited 155mph (on an unrestricted German autobahn, of course) and hit 62mph in 5.9 seconds.

It's all done with the sort of refinement that has made the E-Class the senior management natural choice for decades mixing, as it always has, a sense of restrained class with an ability to simply get on with the job.

So, you won't hear the diesel engine at work, even with the speedometer needle nudging three points territory. Instead, there's a distant murmur of wind noise and a feeling you could go a very long way in this car and still walk, fresh as a daisy, into that critical deal-closing meeting that might make your career.

Compromises to add battery power to the E-Class are restricted to a smaller boot, with a mildly awkward step up in the floor and 400 litres of capacity, down from the 540 litres of the non-electric model.

For an extra £2,000 you could move to the more luggage friendly estate version, with its 480 litres of load space - or a huge 1,660 litres with the back seats folded flat.

Standard kit includes a smooth shifting nine-speed automatic gearbox, reversing camera, LED headlamps, four-way lumbar support for driver and front seat passenger and electric adjustment and heating too, cruise control, DAB radio, satellite navigation and alloy wheels.

AMG Line trim adds additional exterior body styling, 18-inch alloy wheels, black open-pore ash wood trim with Artico Dinamica leather upholstery, an AMG steering wheel with touch control buttons and privacy glass.