THE most fuel-effificient production car BMW has ever produced will be among the model-line-up when the new 1 Series goes on sale in spring.

The introduction of a three-door model and a revised five-door come as a raft of new fuel-saving innovations are rolled out across the range.

Technologies such as Brake Energy Regeneration, Automatic Start-Stop function and Electric Power Steering are combined with a gearshift change indicator to encourage economical motoring.

These innovations are in addition to the use of variable valve technologies and High-Precision Direct Injection engines on some 1 Series models that boost power output but cut fuel consumption and emissions.

The BMW 118d, BMW's most economical car, manages its record 60.1mpg figure courtesy of these features in conjunction with the use of further lightweight engineering. The car now has an aluminium crankcase to save weight.

Aside from the BMW Hydrogen 7, the BMW 118d also posts the lowest ever CO2 emissions of any BMW recording 123g/km (putting it into the Band C category for Vehicle Excise Duty).

Other engines in the new 1 Series range record economy improvements of up to 24 per cent compared to the previous model, while emissions have also been cut by up to 21 per cent.

Yet the new 1 Series is powered by a range of engines whose outputs have increased by up to 20hp with a consequential improvement in performance figures.

The new 1 Series comes with Automatic Start-Stop function to cut fuel consumption. Standard on all manual transmission models (except 130i), the system automatically switches the engine off when the vehicle is stationary and the driver puts the car into neutral. To restart the driver only need engage the clutch again before pulling away in the normal manner. Should he not want to use the Automatic Start-Stop function it can be manually switched off.

The use of Electric Power Steering results in a 90 per cent energy saving compared to a conventional mechanical hydraulic steering system. Power assistance is now provided by an electric motor that works only when required, such as turning a corner.

The plethora of new technology showcased in the BMW 1 Series will have a significant impact on cost of ownership for customers. For the company car driver, all but two engine variants now sit in the Band C category for Vehicle Excise Duty. This results in a saving of up to £505 for someone paying 40 per cent tax and up to £278 for those in the 22 per cent tax bracket. For all owners fuel consumption improvement means a 12,000-miles-a-year driver will save about £250 off the fuel bill.

To herald the introduction of the latest generation of engines, BMW's designers have refreshed the interior and exterior styling of the five-door model.

Inside, customers will also be able to choose between either a four-seat or a five-seat configuration. In the four-seat arrangement rear passengers are separated by a central storage compartment and sit in more sculptured seats. As a no-cost option, the five-seat layout offers the traditional bench seat standard on the five-door 1 Series. The introduction of higher quality materials and minor changes to the layout of the interior enhance customer comfort and practicality.

The new 1 Series comes with MP3 and USB stick capability. Customers with their favourite music loaded on an Apple iPod or a USB stick can now plug these into the car. Tracks are selected via steering wheel controls or the iDrive system.