AT first glance it's a traditional, large saloon - the Audi A6, favoured business express and luxury family mile-eater.

And so it is. But whereas a few years ago it would most likely be powered by a diesel two litre or, perhaps, a three litre turbo, today it gets a 2.0-litre petrol plug-in hybrid up front.

Still elegant, and nicely proportioned despite the onset of time - the current A6 design is now six years old - the switch to electrification has reduced fuel consumption and sharpened performance without noticeable harm to torque or general usability. And there's the added appeal of quieter running and refinement.

With 295bhp to call on it's not surprising there's spring in the large saloon's step. Acceleration is pretty nifty with 62mph coming up in around six seconds. But the emphasis is more on luxury rather than sportiness.

The four cylinder engine remains pleasantly subdued and muted until the revs mount when a degree of coarseness creeping in.

Overall though, the big Audi is one of the most restful, competent long distance saloons this side of £100,000 and it's in its element munching motorway miles or sweeping A-roads.

It starts off in electric mode and has enough juice from the 14.1 kWh battery for around 40 miles. Company drivers will be pleased with CO2 emissions of 31g/km which equates with low BiK taxation.

A full charge on a three-pin plug takes about seven hours which means overnight charging is an easy answer even without a wallbox.

The 50 TFSI e quattro in Black Edition form as driven here comes with Audi's quattro 4WD and a seven speed twin clutch automatic gearbox. Extremely quiet in EV mode - as you'd expect - there's a minor tremor when the ICE unit comes into play.

Ride feels a tad firmer than the standard A6, partly due to adjusted springing to account for the hybrid's additional weight. But it remains a comfortable cruiser with decent bump absorption.

A penalty of hybridisation is reduced luggage capacity to enable the necessary electrification to be houses. The conventional rear boot is down in capacity from 530 litres to a quite modest 360 litres.

The cabin is classy and very typically Audi in layout and styling. High grade plastics, solid , well-made switchgear and controls and an easy to operate screens. The fascia design is very much horizontal with sweeping curves and no sharp angles - all very restful and yet driver orientated.

It has to be said, there isn't an abundance of stowage space within the front cabin - a shallow central dividing box, glove box in front of the passenger seat and fairly slender side pockets. Most families will quickly fill these with their inevitable clutter.

Make the most of its regenerative braking and the hybridisation and fuel is sipped at a modest rate. We were satisfied with our average of 38mpg over the 450-mile test period.

Quieter and more comfortable than many so-called prestige models, this A6 easily spans the higher price-bracket with its exceptional refinement and ease of driving.