Available to order now with first deliveries due in December, the A6 2.0 TDI ultra saloon with S tronic twin-clutch transmission now offers an official fuel economy figure of up to 67.3mpg and has cut its emissions to 109g/km in SE form with 17-inch alloy wheels.

In the more sporty S line specification, which includes 18-inch alloy wheels, it offers the same economy whilst its emissions increase very slightly to 110g/km.

Meanwhile TDI ultra SE Avant versions gain an improved CO2 figure of 114g/km for S tronic models, equating to a combined fuel economy figure of 61.4mpg, or 118g/km and 60.1mpg for versions equipped with manual transmission.

Priced from £31,955 OTR in Saloon form or £33,955 as an Avant, the models still bring strong and responsive performance thanks to peak outputs of 187bhp and 295lb.ft, the latter available between 1,750 and 3,000rpm. As a result the S tronic saloon delivers a 8.2-second 0-62mph time (8.4 seconds for manual ultras) and 144mph top speed.

Thanks to its increased efficiency, the TDI ultra saloon in SE form with S tronic transmission benefits from a BiK rate change from 18% to 17%, equating to a liability for a 40% tax payer of £2,273 in the first year. Manual transmission models with their reduced 113g/km output and 65.7mpg economy are only just above at 18%.

Both ultra versions of the new A6 saloon also move from VED band C to band B for road tax, reducing the first year cost down to zero and giving a £10 annual saving thereafter compared to the outgoing model at just £20 per year.

The efficiency gains have been brought about by the fully redeveloped seven‑speed S tronic twin-clutch transmission, which replaces the familiar eight-speed multitronic CVT in front-wheel drive models and brings rapid fire gear changes and a new “coasting” function. Ultra models can also be specified with a newly designed six‑speed manual gearbox, which is notable for its particularly light weight and low friction characteristics. 

Improvements to the engine start-stop system also contribute to the efficiency gains along with weight-saving measures in the suspension of the A6 Avant TDI ultra models, which feature new lightweight Glass Fibre Reinforced Polymer springs as standard.

The ultra models are joined in the new A6 saloon and Avant ranges by four other versions powered by three V6 TDI engines with varying power outputs and either single or twin turbo charging. All comply with the Euro 6 emission standard.

There are also S6 and S6 Avant versions, available from November for March 2015 deliveries, whilst RS6 Avant availability for ordering is to be confirmed but is expected in the first quarter of 2015.

Other changes to the refreshed A6 include front and rear styling revisions, new interior design as well as new versions of the top-of-the-line MMI navigation plus and Audi connect elements.