THE seventh generation of BMW's 3 Series Saloon is longer, wider and lighter as it seeks to maintain its reputation as the car keen drivers buy when they go looking for a classy compact saloon.

On sale in March from £33,610, the new 3 Series is unmistakeably the latest in the line stretching back to 1975 but is 85mm longer (at 4,709mm) and 16mm wider (at 1,827mm) than before. A stretched wheelbase means usefully more legroom in the rear seats.

The upgraded four-cylinder engines from the BMW Group's Efficient Dynamics family are used in the £37,660 BMW 330i and the £36,800 BMW 320d.

The 3 Series Saloon will feature a new generation six-speed manual gearbox and the eight-speed Steptronic transmission. As an alternative to rear-wheel drive, the BMW xDrive all-wheel-drive system will also be available for the new BMW 320d at launch.

Systematic upgrades have been made to the turbo technology for the two-litre, four-cylinder diesel engines in the BMW 320d and BMW 320d xDrive models.

It now includes multi-stage turbocharging, which brings increased efficiency across all engine speeds. The revised diesel has a maximum output of 190hp enabling the BMW 320d to accelerate from zero to 62 mph in 7.1 seconds (automatic: 6.8 seconds) while the BMW 320d xDrive can get from zero to 62mph in 6.9 seconds.

Average fuel consumption is 64.2mpg (automatic: 67.3mpg) for the 320d and 62.8mpg for the 320d xDrive. The 320d's CO2emissions are 115g/km (automatic: 110 g/km) while the 320d xDrive's CO2emissions are 118g/km.

Overall, the new BMW 3 Series Saloon weighs up to 55kg less than its predecessor. The body itself is 20kg lighter, while aluminium front spring struts and engine subframe have cut 7.5kg from the overall weight. A further weight saving of almost 15kg is due to the use of aluminium for the bonnet and front side panels.

Shoulder room in the front of the cabin has increased, and passengers in the rear benefit from more legroom. The distance between the front and rear seats has been extended by 11 millimetres, and all occupants have more headroom. Getting in and out of the car is easier for the rear passengers because the door aperture height has been increased.

Boot capacity is 480 litres, and its new partitioning into primary luggage compartment and separate storage compartments has created an additional 36 litres of space.

The package and option structure for the new 3 Series has been dramatically simplified, with a package and option list reduced to six main packages and around 10 single options.

The packages group together options which share similar functionality or customerbenefit, and will ease the ordering process while still allowing for a wide degree of personalisation, says BMW.

The M Sport Plus package combines a 19-inch wheel, M Sport brakes (2.0d and 2.0d xDrive) adaptive M suspension, sun protection glazing, M seat belts, black kidney grills, M rear spoiler. The 3.0i models with M Sport Plus also gain the electronic M differential.

A new technology package combines Harman Kardon speakers, head up display, extended Bluetooth with wireless charging and gesture control. The comfort package combines a heated steering wheel, comfort access, automated tailgate and storage compartment features. The premium package includes electric seats with memory, lumbar support and an electric glass sunroof.