With 360 Newton metres of torque and 105 kilowatts, the Mazda 3’s powerplant features a self-cleaning particulate filter trap and Euro Step IV emissions.

The Mazda 3 Diesel is expected to accelerate from 0-100 km/h in 9.5 seconds and comes standard with a six-speed manual gearbox. The transmission is shared with the Mazda 3 MPS, Mazda 6 MPS and Mazda 6 Diesel models.

Fuel economy is not 'top of the class' as with Government fuel tests show that the Mazda 3 Diesel can travel 916 kms on a tank of fuel at its combined average ADR 81/01 fuel test consumption of 6.0L/100km and more than 1,010 kms when on the highway (5.4L/100km).

Priced from $30,500 (RRP) for the Mazda 3 Diesel sedan or hatch, they are available with the same equipment levels found in petrol-powered Maxx Sport models but add Dynamic Stability Control and Traction Control as standard.

The Diesel’s safety package also includes dual front, front side and head protecting airbags (six in total) and ABS anti-lock brakes with Electronic Brakeforce Distribution and Emergency Brake Assist.

The Mazda 3 Diesel shares its 300 mm ventilated front (up 22 mm on the 2.0-litre petrol Mazda 3’s front discs) and 280 mm rear disc brakes (up 15 mm on the 2.0-litre car’s rear discs) with 2.3-litre petrol Mazda 3 SP23 variants.

Standard features include air-conditioning, power windows and mirrors, cruise control, six-disc CD changer, steering wheel mounted audio and cruise controls, reach and rake steering adjustment and an iPod compatible AUX jack.

Like the petrol Maxx Sport models, the new Mazda 3 Diesel, which can be identified by MZR-CD badges on both front doors, also features a body kit and 16x6.5 alloy wheels.

To translate the MZR-CD 2.0 turbo diesel’s torque into controllable and reliable traction, Mazda’s engineers stiffened the car’s chassis installing special body shell reinforcements from the high-performance Mazda 3 MPS – the front suspension upper plate, front cowl member and middle tunnel cross member have all been improved.

The driveshafts have also been upgraded to handle the additional 178 Nm of torque produced by the diesel engine over the Mazda 3’s 2.0-litre powerplant (that engine’s torque peaks at 182 Nm).

Mazda 3 Diesel’s MacPherson strut front suspension and multi-link rear suspension feature unique calibration, and the front and rear stabilisers have grown by 2 mm to 23 mm and 22 mm respectively.

Taken together these chassis features provide superior road holding and even more linear steering response from the car’s hydraulic power assist steering system.

Managing director of Mazda Australia, Doug Dickson, said: “With the introduction of the Mazda 6 Diesel in October last year, Mazda became the first and remains the only Japanese car maker to introduce a state-of-the-art diesel engined passenger car."

“The sales success of the Mazda 6 Diesel convinced us that a Mazda 3 Diesel would find a ready market here."

“Our own research confirmed this. Mazda’s target customers, the so called high involvement buyers – Australians interested in the driving experience – said they are attracted to diesel for the technology as well as the potential fuel gains."

“And recent Roy Morgan data shows that 60 per cent of our target customers would consider purchasing a diesel powered car in the next year. But only 47 per cent of them would consider a hybrid."

“The Mazda brand and our vehicles have strong appeal with high involvement buyers, therefore research such as the Roy Morgan data further validates our decision to broaden the availability of this engine technology by offering it in our most popular model, the Mazda 3."

Mazda Australia expects to sell 130 Mazda 3 Diesel models a month with the sedan split likely to mirror the petrol variants, taking about 70 per cent of the business.

Diesel Technology

The Mazda 3’s diesel engine is a Mazda designed and built MZR-CD 2.0-litre common-rail turbo diesel engine that uses various technologies to ensure that it comfortably meets Euro Stage IV emission standards.

Utilising a state-of-the-art ceramic filter system to capture particulate matter, the Mazda 3’s diesel engine virtually eliminates diesel smoke.

Once the filter has captured a pre-determined amount of particulate matter exhaust gas temperatures are raised to burn it off and regenerate the filter.

Common-rail fuel injection

The MZR-CD engine’s common-rail fuel injection system injects fuel at an pressure of 1,800 bar (180 MPa, 26,100 psi). The required fuel for injection is accumulated under a pressure of up to 180 MPa in the common-rail. Fuel injection volume, frequency and timing are optimised by electronic control based on throttle opening and engine speed data.

Relatively low combustion ratio

The MZR-CD’s low compression ratio (16.7 to 1) allows low-temperature pilot premixed combustion, also reducing soot and NOx emissions.

Fuel is injected into each combustion chamber before the piston reaches top dead centre, promoting combustion efficiency while minimising production of particulate matter or black soot. In addition, the lower combustion temperature helps to minimise NOx.

To enable optimal control of the air/fuel ratio, a high response intake shutter valve and a valve to control the recirculation rate from the exhaust gas recirculation (ERG) cooler are located on the intake side of the engine. Residual oxygen in the exhaust gases is monitored by an O2 sensor and this information is utilised by a 32-bit powertrain control module to optimise the fuel/air ratio, continuously optimising the mix and suppressing NOx.

A catalysed diesel particulate filter reduces black smoke emissions to virtually zero by capturing particulate matter in a ceramic filter. When a specific quality of particulate matter is trapped it is automatically burnt off, allowing the filter to return to its original efficiency.

The particulate filter enables the MZR-CD engine to cut its soot emissions to 80 per cent below the Euro Stage IV emission standard.

The relatively low compression ratio also reduces pumping loss and promotes thermal efficiency. Typically a low compression ratio means inferior thermal efficiency under low-load conditions, but this is offset by a combination of high fuel injection pressure and the frequency and timing of the multi-stage injections.

Variable Geometry Turbocharger

The engine also features a variable-geometry turbocharger that has a lower inertia moment and features a short distance between the exhaust gas inlet and the centre of the turbine shaft.

A variable-geometry turbocharger helps maximise torque over the widest range of engine speeds. The Mazda 3’s VGT is an update of earlier designs with the size of the turbine reduced to lower the inertia moment by 14 per cent. In addition the ratio between the cross sectional area of the narrowest part of the VGT’s exhaust gas inlet and the distance from the centre of that area to the centre of the turbine shaft has been reduced, producing smoother acceleration, a 10 per cent power jump, a 10 per cent improvement in maximum torque and better fuel economy.

The variable-geometry turbocharger is combined with the engine’s high pressure common-rail fuel injection system, with optimised injection volume and multi-stage injection of up to nine times per cycle and a relatively low compression ratio, all of which improve output and torque, repress combustion noise and reduce emissions.

High torque, low NVH

The new turbocharged 2.0-litre MZR-CD engine has been developed to deliver high torque while minimising noise, vibration and harshness (NVH).

Multi-stage injection, which is performed up to nine times per cycle, prevents overly rapid pressure increase in the cylinders, suppressing diesel knock and other combustion noise.

When the engine is idling the intake shutter valve restricts air intake volume to reduce cylinder pressure by about 25 per cent and suppresses idle knock, while the low compression ratio limits engine speed fluctuations and significantly lowers vibration.

Pricing

Mazda 3 Diesel sedan $30,500 (RRP)

Mazda 3 Diesel hatch $30,500 (RRP)