THE new BMW 1 Series goes on sale this spring and features a model line-up that includes the most fuel-efficient production vehicle BMW has ever produced.

The introduction of a three-door model and a revised and face-lifted 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 lower rolling resistant tyres and 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.

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 £100pa 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.

These improvements have not been to the detriment of driving pleasure. 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.

BMW's baby is potent - the 130I, with the world's lightest six-cylinder production engine, achieves 0-62mph in 6.0 seconds (five-door is 6.1 seconds) and an electronically limited top speed of 155mph. Output is 265bhp while peak torque is 315Nm. Combined fuel consumption is 34.0mpg and CO2 emissions are 197g/km.

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.

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.

The 1 Series now features a larger kidney grille for improved airflow to the engine. The lower front spoiler has also been reprofiled to create a larger air intake.

The new three-door 1 Series features the same styling cues but its side view is naturally different. The passenger doors are longer than those on the five-door model and are also frameless in the style of a coupe.

Inside, customers will also be able to choose between either a four-seat or a five-seat configuration.

The new three- and five-door BMW 1 Series models will be on display at the Geneva Motor Show in March and go on sale in the UK at the same time.