Available from early 2014, the new “ultra” versions use the 2.0-litre TDI with either 136 or 163hp, giving a combined fuel consumption rate of 3.9 to 4.6l/100km and CO2 emissions of 104 to 119g/km. Meanwhile the engine also uses an SCR system to remove nitrogen oxides, ensuring the new ultra models meet the forthcoming Euro6 emission standards

The carmaker added that the improvements in efficiency have been effected without any impact on driving dynamics or comfort.

Audi board member for development, Prof Dr. Ulrich Hackenberg said: ‘The latest TDI technology, ultra-efficient transmissions, advanced exhaust aftertreatment – customers will hardly see anything, but they’ll notice the effects of powerful acceleration and, thanks to extremely low fuel consumption, when paying at the gas station. The Audi ultra models score points with big advantages for everyday operation – just what customers appreciate.’

As well as using the 2.0 TDI engine and standard start-stop system, the A4, A5 and A6 ultra models feature a six-speed manual transmission with taller ratios on higher gears. There’s also an optional seven-speed S tronic dual-clutch transmission on the A6 that further reduces the average consumption rate to 4.4l/100km and emissions to 114g/km (4.6l/100km and 119g/km on the Avant).

Meanwhile the A4 and A4 Avant also use aerodynamic modifications and a lowered body.

All models are marked out with "ultra" branding at the rear.

The ultra range also includes the A3 1.6 TDI ultra, which made its debut as the first ultra model last autumn and offers 3.2l/100km and 85g/km.

The new ultra models will go on sale from the first quarter of 2014. The 136hp version of the A4 starts at €32,600, the A4 Avant at €34,250. With the 163hp engine, prices for the A4 begin at €34,700, the A4 Avant €36,350. The A5 Sportback is available for €37,350 and the A5 Coupé for €38,150. The A6 is priced at €39,900, the A6 Avant at €42,250; the prices for both model versions with S tronic is €2,250 more.