A special Efficient Dynamics variant of the 520d will be launched in the next few months to set a new performance benchmark in the segment, Fleet News can reveal.

The car will use a modified version of the 2.0-litre engine that allows the 320d ED model to combine near-70mpg economy with tailpipe emissions of 109g/km. In the bigger 5 Series, it is expected to deliver more than 60mpg and sub-120g/km emissions.

“We are expecting the new Audi A6 to be a strong competitor when it arrives next year and we need to respond.

“Our colleagues in Munich are working hard to develop a product that will have special significance in the UK and we are confident it will hit all the right thresholds in the segment,” said BMW UK sales director Sean Green.

Speaking as the company announced a 12.3% rise in sales up to November, Green said a 33% growth in incorporate registrations had more than compensated for a 10% fall in retail business.

“Over the last two years, a lot of people have put the brake on company purchases but they have now come back into the market. Corporate registrations have grown to 59% of our total volume this year, largely due to the success of the 320d ED and 520d models.

“But though we expect an additional 5,000 sales from the new X3 in 2011, we don’t anticipate maintaining the same level of growth,” he said.