BMW has announced a host of detail changes and new models across its range of cars, with improvements in efficiency and specification at the core of the changes.

Of most interest is the new 520d Efficient Dynamics, which improves on the existing 520d model to deliver a remarkable set of figures.

While the 182bhp power output is unchanged, changes to the drivetrain and a dedicated Eco-Pro mode allow it to achieve 62.8mpg combined and an emissions figure of only 119g/km, yet it can still achieve a 0-62mph time of 8.2 seconds.

The 520d ED is available from September starting at £30,435.

The Z4 Roadster now has a new four-cylinder engine using twin-turbochargers, and comes in two power outputs to replace the previous four and six-cylinder models.

The sDrive20i has 182bhp, can reach 62mph from rest in 6.9 seconds and a top speed of 142mph and at the same time can deliver emissions of 159g/km and fuel consumption of 41.5mpg combined.

The sDrive28i has a higher output of 242bhp, cutting the 0-62mph time to 5.6 seconds and pushing the top speed to 155mph yet it achieves the same emissions and economy as the sDrive20i.

The Z4 also benefits from an enhanced specification, with Bluetooth and a USB connector now standard. sDrive20i models also gain leather seats.

The rest of the 5-Series range is enhanced in a similar manner with the same efficient petrol engines, while the 6-Series will be available in coupe form as well as with diesel power.