Audi has unveiled pictures of the new A6 saloon which will match the latest BMW 520d for CO2 emissions when it goes on sale in 2011.
The new model, which will be available to order from January, uses a combination of lightweight aluminium for some bodywork to help the 177bhp 2.0 TDI model achieve 129g/km - the same figure as the current 184bhp BMW 520d saloon.
Combining the two materials reduces the shell weight by around 15%, and enables the A6 2.0 TDI to tip the scales at a relatively modest 1,575kg.
Prices for the new model will start at £30,145 on the road, with first customer deliveries beginning in spring 2011.
Other versions available from launch will include 204bhp and 245bhp 3.0 TDI models, as well as a petrol powered 300bhp 3.0 TFSI, while Audi is also planning a petrol-electric hybrid version using a 2.0T petrol motor.
The new model will measure 4.92m long and include features and technology first seen in the latest A8 luxury saloon launched in 2010.
Two specification levels – SE and S line – will be offered in the UK, each including alloy wheels, leather upholstery, cruise and front and rear parking controls, SD-based satellite navigation, Bluetooth phone preparation, split/folding rear seats and light and rain sensors.
S line models will add larger 18-inch alloy wheels, xenon headlamps with LED daytime running lamps, sports suspension, upgraded Valcona leather upholstery and an exclusive S line exterior and interior styling treatment.