Motoring editor Andy Russell is impressed by how Audi's A6 ultra diesel munches miles but sips the fuel.

On the back of certain Audi A6 models, under the TDI badge, is an additional label that states in small letters 'ultra'. It's a small badge but says a lot about the German car-maker's continual striving to produce leaner and cleaner engines.

This is the A6 fitted with the latest version of the 2.0-litre TDI turbo diesel engine. Now developing 190PS, compared to the standard version's 177PS, it also sees official combined fuel economy rise to 64.2mpg and CO2 emissions fall to just 114g/km – improvements of up to 14% – for the saloon in combination with the new seven-speed S tronic automatic gearbox – now joined by a six-speed manual transmission.

And, with the A6 an executive express that finds favour with many company car drivers, their benefit-in-kind tax liability starts from 18% which adds to the appeal and lower overall costs.

But don't for a moment think the A6 2.0 TDI ultra sacrifices MPH for MPG – it is no slouch, capable of reaching 62mph from rest in a little over eight seconds and a top end more than double the maximum speed limit.

It certainly feels brisk to drive, picking up cleanly and enthusiastically from low revs with strong mid-range punch which makes for relaxed cruising and safe, simple overtaking. The new DSG twin-clutch automatic gearbox, which replaces the eight-speed multitronic CVT transmission in four-cylinder models, goes up and down the box so smoothly and efficiently you barely notice the shifts, only the engine note changing.

In everyday driving I saw 53 to 58mpg overall and 65mpg on a gentle run. For a four-cylinder diesel engine it is refined and quiet on the go and, for most drivers, it has more than enough power and performance.

Being an Audi, the A6 has the German giant's exquisitely tasteful interior with upmarket materials, clear simple dials and controls and a level of technology that is useful rather than unnecessary.

The A6 wafts along so, combined with a large fuel tank, can cover huge distances comfortably and even the S line version's bigger 18in alloy wheels and 20mm lower sports suspension do not make the ride unduly firm but more dynamic to drive, although there is noticeable tyre noise on poor surfaces.

The saloon's long 530-litre boot has wide access to swallow luggage and rear seat backs drop 60/40 for longer loads.

Available in SE, S line and Black Edition, the A6 comes with a comprehensive kit list.

The A6 ultra munches the miles while sipping the diesel – and that makes this stylish, elegant range even more attractive.