It says the 3 Series has more space and comfort than before and is better to drive than its main rivals, the Audi A4 and Mercedes-Benz C-Class.
It will go on sale here next year. It is unclear if XDrive will be available in right-hand-drive.
The 3 Series is BMW's most important model, both in terms of numbers sold and as a flag carrier for the company's reputation for quality, reliability and desirability.
BMW says it will have eight versions of the 3 Series on sale in different markets by March that emit less than 120g per kilometre of CO2.
Towards the end of 2012, BMW launches XDrive four-wheel-drive versions and the ActiveHybrid 3 which is essentially a 335i with a 40kW electric motor.
Many of the new features introduced in the new 5 Series and 1 Series have made their way into the 3 Series, including eight-speed automatic transmission, stop-start, electric-assisted steering, four selectable driving modes and a multi-function screen driven by the iDrive console knob.
The new 3 Series has been under development for longer than almost any other BMW. It was first spied testing early in 2009.
Weight has been reduced by a claimed 50kg compared to the previous model and the drag coefficient is down to 0.26 thanks to improvements in the aerodynamics.
These tweaks include a streamlined underside, covers which create a diffuser effect at the rear and channels in the front bumper which reduce the turbulence created by the front wheels.
The new 3 Series also features a much stiffer body and an all-new chassis with a longer wheelbase (up 50mm to 2810mm), with wider tracks (up 37mm at the front and 47mm at the rear) to improve handling.
Overall length has increased by 93mm and there's more space inside.
The exterior design has been inspired by the 5 Series. The new car's lights, flusher radiator grille and L-shaped LED taillights represent the biggest changes.
Under the skin, the chassis gets an updated version of the company's five-link suspension at the rear and more aluminium in the front set-up for lower unsprung weight.
BMW says the new suspension improves on the car's handling by making it even more agile and stable but with better ride comfort.
All models get new electric-assisted power steering to cut weight and improve fuel efficiency. BMW claims it is just as accurate and has as much feedback as a conventional hydraulic system. However, its Variable Sport steering will be available as an option, as will Adaptive M Sport suspension with electronically variable dampers.
The dashboard is angled toward the driver, but the iDrive controller and the 6.5-inch display screen that accompanies it (both are standard across the range) are arranged in the centre.
For the first time, BMW owners will be able to personalise their cars as the 3 Series takes its lead from the latest 1 Series with the addition of Sport, Modern and Luxury trim levels to standard ES, SE and M Sport versions.
The new car is loaded with gadgets. All models come with Drive Performance Control, allowing the driver to swap between fuel-thriftier EcoPro (which electronically backs off the throttle), Comfort, Sport and Sport+ (the latter available on Sport models).
All cars have stop-start too. Other gadgets making their 3 Series debut include Park Assist, which steers the car into a parallel parking spot, a Head-Up display showing speed limits, and Dynamic Safety, which tensions the seatbelts and closes any open windows if it senses an imminent accident.
The new 2-litre four-cylinder TwinPower petrol engines and 2-litre diesels will almost certainly kick off the new model when it lands in New Zealand.
The TwinPower petrol units are likely to arrive under the bonnet of the 320i and 328i, where respectively they will deliver 135kW and 180kW.
The 328i's engine develops its 180kW at 5000rpm and 350Nm of torque from a low 1250rpm, pushing the car from zero to 100km/h in 5.9 seconds.
Fuel economy comes in at a claimed 6.4 litres/100km, down 11 per cent on its predecessor. BMW says the 328i's CO2 emissions have been cut to 147g/km.
BMW has also trimmed the thirst of the 3-litre TwinPower inline six-cylinder petrol engine of the 335i by also shaving 0.1 seconds off its 0-100km/h sprint time.
Maximum power of 225kW is achieved at 5800rpm, while peak torque of 400Nm is on stream between 1200 and 5000rpm.The 0-100km/h sprint now takes 5.5 seconds - a fraction faster than before - although the automatic version with the new eight-speeder is said to be 0.3 seconds faster.
The 335i fuel consumption is now a claimed 7.9 litres/100km for the manual (CO2 emissions at 186g/km), while the automatic achieves 7.2 litres/100km and a CO2 rating of 169g/km.
In the diesels, power and torque of the 320d are unchanged at 135kW at 4000rpm and 380Nm between 1750 and 2750rpm.
But the manual and automatic 320ds' average fuel consumption are both now 4.5 litres/100km, with CO2 emissions improved by 118g/km - again 14 per cent for the manual and 16 per cent for the automatic.
The 320d Efficient Dynamics Edition develops less power but the same 380Nm of torque.
Fuel consumption is a claimed class-leading 4.1 litres/100km, with CO2 emissions of 109g/km.
