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The crankcase jacket, bedplate and cylinder head cover are all made from magnesium, which weighs 30 per cent less than aluminium.

Additionally, the new 3.0-litre unit is the first six-cylinder engine to feature BMW's patented VALVETRONIC induction system. First seen on BMW's V8 engines and more recently offered as standard on the Hams Hall four-cylinder petrol engines, VALVETRONIC infinitely varies the intake valve opening times and, when combined with Bi-VANOS variable camshaft timing, delivers the optimal fuel efficiency and engine response.

Also joining the six-cylinder model range in spring 2005 will be the 325i, delivering 218bhp at 6,500rpm and 250Nm (184lb-ft) at 2,750 - 4,250rpm.

The new 3 Series range will also feature a two-litre diesel and a two-litre petrol variant at launch. The BMW 320d, currently the UK's most popular 3 Series model, features second-generation common rail diesel technology and a variable vane turbocharger to deliver 163bhp and 340Nm (251lb-ft) of torque. This provides the car with the best of all worlds. Acceleration to 62mph is achieved in 8.3 seconds with a top speed of 140mph. While delivering this level of performance, it also achieves 49.6mpg on the combined cycle and, as an additional benefit to the company car driver, is EU4 compliant.

The engine in the new 320i is based on that of the outgoing 318i, but with enhancements to the induction and exhaust systems.

This enables the car to accelerate to 62mph from standstill in 9.0 seconds, achieve a top speed of 136mph yet still delivering a frugal 38.2mpg.

Further four-cylinder 3 Series variants will follow during the course of 2005.

Soft Stop is also incorporated which modulates the brake application to prevent the nose of the car from 'diving' when travelling slowly.

Also included in DSC+ is a Start-Off Assistant that uses the clutch to prevent the car from rolling back on a hill-start and a brake detector that ensures the discs are kept dry and responsive on wet roads.

Also assisting the car's agility is BMW's Active Steering system, available for the first time in a car of this class. Previously only available on larger 5 and 6 Series models, Active Steering is offered as an option on six-cylinder models and resolves the conflict between low-speed agility and higher-speed stability by delivering a speed-proportional steering ratio. Active Steering also brings a number of key safety benefits. In conjunction with the DSC+ system, if the car detects oversteer, Active Steering applies a small amount of positive steering angle to bring the rear of the car back into line. Additionally on the new 3 Series, when applying the brakes on a surface with differing grip levels such as snow or ice, Active Steering intervenes to stabilise the car more precisely and quickly than the driver is able to do manually.

Supporting these steering and traction control systems is a chassis that has been tuned to deliver optimal driving dynamics on all road conditions. With BMW's trademark front engine - rear-wheel-drive layout and near-perfect 50:50 weight distribution, the new 3 Series feels nimble and agile on the road. Its double-joint spring strut front axle is made completely of aluminium, minimising the unsprung mass of the car and reducing road noise. The new five-arm rear axle, first seen on the new BMW 1 Series, delivers excellent ride comfort.

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The new 3 Series body is stiffer yet lighter than that of the outgoing model. Thanks to a new joint and crossbar arrangement for the car's load-bearing structure, the bodyshell stiffness is increased by 25 per cent over its predecessor.

The inherent rigidity of the steel bodyshell enhances the new 3 Series' class leading safety levels. With the addition of six airbags as standard, including curtain head airbags for front and rear occupants, the car is expected to receive a five-star Euro NCAP rating. It is also one of the first cars in the world that is fully prepared for the rigorous side impact requirements in North America as well as the US high-speed rear impact test.

Also supporting these high standards of safety are a number of familiar systems from other BMW models. Brake Force Display is standard for the first time on 3 Series Saloon models, offering two stage brake lights. Brake lights illuminate normally in average driving conditions but during an emergency stop or when the ABS braking cuts in, the area of brake light illumination increases to warn those travelling behind of the situation ahead.

Adding further to safety levels are Run-flat tyres, available for the first time on 3 Series models. Like the 1, 5 and 6 Series models, Run-flat tyres are offered as standard, and with the recent developments in Run-flat technology, the car can now be driven for an astonishing 150 miles at 50mph with up to four punctured tyres. This allows the driver to complete almost any journey before replacements need to be sought.