If the diesel engine really is in its dying days it shows absolutely no signs of going quietly.

The latest turbocharged unit slotted into the new Audi A6 saloon delivers every bit of refined performance that you would expect to power an elegant business class saloon.

Yes it has four cylinders and is only 2.0 litres, but the engine’s vital statistics make for some comforting calculations for business users.

It might develop 204 horsepower and have a potential top speed well in excess of twice the motorway limit, but the truly eye-catching figures are the combined 62.8mpg and carbon dioxide emissions of just 117g/km.

Even better news is that the four-cylinder ‘mild hybrid’ model, mated to a seven-speed semi-automatic gearbox, is equipped to the same high level as its six-cylinder counterpart, with the latest technology blended with a focus on luxury and comfort.

The interior of the new Audi A6 is even larger than the outgoing model. Legroom in the rear exceeds its predecessor, while headroom and shoulder room are also more generous.

And it is that combination of space, pace and polish that have made the A6 a natural choice for high-mileage drivers looking for a swift, calm and reassuring ride, with handling in the new model even sharper than before.

The latest model with its long bonnet, long wheelbase and short overhangs, uses a series of sharp edges and striking lines to emphasise its dynamic character.

The S line specification car driven here came with lowered sport suspension, larger 19-inch alloy wheels, S line body detailing and adaptive matrix LED headlights that automatically stay on high beam while preventing dazzle to oncoming drivers.

But it is inside that the technology packed into the car really starts to make itself felt. The dashboard is dominated by two large touchscreen displays. The car driven here had the top-level technology pack fitted bringing with it a 10.1-inch upper screen, map quality navigation system, fully digital instrumentation and wireless charging for compatible smartphones. Online services have been expanded to include features such as natural voice recognition and personal route assistant.

Standard equipment include electronic driver assistants such as a parking system with rear-view camera; pre-sense front collision warning and automatic braking system and a lane departure warning system.

Audi is also lining up a host of driver assistance systems – no fewer than 39 in all – that will cover everything from improved safety and economy to parking. One James Bond-style system will allow you to autonomously manoeuvre the car into and out of a parking space or garage while outside the car by using the myAudi app on a smartphone.

Depending on what systems you opt for, Audi says the car could end up fitted with no fewer than five radar sensors, five cameras, 12 ultrasonic sensors and a laser scanner.

With technology continuing apace, part of the improvements in economy are down to a new ‘mild hybrid’ drivetrain that allows the car to recover up to 5kW of power during deceleration and store it in a separate lithium-ion battery housed in the rear of the car. If you take your foot off the accelerator while cruising, the car can also coast with the engine running at idling speed. As soon as you accelerate again, the system restores power quickly and smoothly.

The 2.0-litre TDI engine driven here is also available in the A7 Sportback  ̶  the first time a four-cylinder has been fitted in the elegant five-door coupé. All versions of the A6 and A7 are initially front-wheel-drive, with four-wheel-drive versions on the way.

Auto facts

Model: Audi A6 40 TDI S line S tronic

Price: £45,655 as tested

Insurance group: 33E (1-50)

Fuel consumption (combined): 62.8mpg

Top speed: 152mph

Length: 493.9cm/194in

Width: 188.6cm/74.2in

Luggage capacity: 18.7 cu ft

Fuel tank capacity: 13.8 gallons/63 litres

CO2 emissions: 117g/km

Warranty: Three years/ 60,000 miles