BMW's 1 Series has undergone a major transformation which is more than a mere facelift.

The German car maker says it's a completely new model, despite retaining its basic shape.

It has a new chassis, is more spacious, has new engines available and comes with a lot of new gear.

The 1 Series remains the only rear-wheel drive motor in its class and has proved extremely popular with UK drivers. Sales here are second only to those in its homeland.

It goes on sale over here on September 17 with prices starting at £19,375.

Although there's no dramatic change to the body shape it does look much sportier, with flared rear wheel arches, sculpted door panels, re-shaped headlamp units and three-section air intake. The kidney grille is tilted forwards giving it a thrusting stance.

Inside, rear seat passengers will find more leg and headroom and luggage space has been increased by 30 litres to a maximum of 1,200 litres with the rear seats down.

The five-door, which will be on sale first, has rear doors which open wider allowing easier access, which was a problem on the original 1 Series.

Interior design is still excellent with quality materials for seating and panels and BMW's iDrive system is available as standard on cars with SE specification and above, comprising of a controller on the centre console and a freestanding, high-resolution 6.5 inch flat screen monitor.

This display is used for all information, entertainment, telecommunications and navigation functions, should you take the satellite navigation option.

From launch the new 1 Series will offer a choice of two, new generation, four-cylinder petrol engines and three, redesigned, four-cylinder diesel units.

For the first time, a BMW four-cylinder petrol engine has been fitted with TwinPower Turbo technology.

For petrol lovers the 118i produces 170 bhp and can sprint from zero to 62 mph in just 7.4 seconds and on to a top speed of 140 mph.

Combined fuel consumption is claimed at a creditable 47.9 mpg, and CO2 emissions of 137g/km.

Diesel fans will probably go for the 118d which has an output of 143 bhp. It accelerates from 0 to 62mph in 8.9 seconds, with a maximum speed of 132 mph, yet manages 62.8 mpg.

There's a choice of six-speed manual or automatic gear changes on most of the models and all include a raft of electronic systems to increases both driving enjoyment and safety.

These include optional Variable Sports Steering; Driving Stability Control including Dynamic Traction Control and an electronically locking rear differential as standard.

DTC is activated in DSC Off mode, applying brake force to either rear wheel in the advent of wheelspin to maintain traction through a corner.

A new feature is Eco Pro which changes the engine, gear shift and accelerator settings by means of a switch which allow you to choose a driving mode from Eco Pro (the most fuel-saving), Comfort, Sport and on some models Sport Plus.

As far as ride and handling go BMW has always been on top of the game and the new 1 Series is no exception.

There was some criticism of the outgoing model as far as the firmness of ride was concerned but this time the German engineers have improved the setup specifically to cope with UK road conditions.

My driving companion on the test drive near Berlin owned a 1 Series and he was very impressed with the improvements. On a 10-mile stretch of pretty rough surfaces the new Beemer ironed out the potholes remarkable well.

Standard equipment on all models include auto Start-Stop, 16-inch light alloy wheels, four airbags, BMW Business radio with single CD player, air-conditioning, 60-40 folding rear seats, child seat ISOFIX attachments, cloth upholstery and leather steering wheel.

The base model is badged as ES and other specifications are SE (which is just £650 more), Urban and Sport.

Depending on the spec they can add various goodies to the 1 Series including the high-resolution 6.5 inch flat screen monitor, Bluetooth hands-free facility with USB audio interface and a multi-function leather steering wheel with speed limiting function, dark chrome exhaust pipe and high-gloss black kidney grille, central air intake trim, side intake surrounds and rear bumper trim.

Prices start from £19,375 for a BMW 116i ES rising to £24,720 for a BMW 120d Urban or a BMW 120d Sport.

The three-door model will follow early next year as will an M version which is scheduled to make its appearance in March, 2012.