Diesel First For Mazda6

Image Gallery

1. Overview

From this month Mazda adds a state-of-the-art, ultra-clean, diesel powered Mazda6 hatch and wagon to its award winning car range.

This makes Mazda, which is the country’s top-selling full-line importer, the only Japanese car maker offering a diesel passenger car in the fuel-sensitive Australian car market.

With the Mazda6 Diesel hatch and wagon consuming on average just 5.9L/100km -- according to government fuel economy tests -- the diesel Mazda6 models can travel more than 1000 kilometres on a tank of fuel.

Fuel economy is even more impressive on the highway with consumption for the hatch and wagon falling to just 5.0L/100km, giving a potential cruising range of more than 1250km from the 64 litre tank.

Combining with a six-speed manual transmission, the Mazda6’s engine features the latest diesel technology and backs up its impressive fuel economy with strong performance and clean exhaust emissions.

The direct injection and turbocharged Mazda6 diesel also promises a sporty drive with the Mazda designed, engineered and manufactured 2.0-litre, direct injection engine producing a class-leading 360 Newton metres of torque (pulling power). The engine also develops a strong 105 kilowatts.

The Mazda6 hatch diesel accelerates from 0-100kmh in just 9.5 seconds.

Mazda is offering buyers not only two body styles but the choice of different trim levels.

The Mazda6 Diesel wagon, which is priced at $35,205 comes with climate control air-conditioning, 16-inch alloy wheels, a leather-wrapped steering wheel, trip computer, six-stack CD, wheel-mounted audio and cruise control switches and more luxurious trim, remote central locking with deadlock function, power windows and mirrors, driver’s seat height adjustment and telescopic and height adjustable steering.

The diesel-powered hatch, which is priced at $38,090, also gains a number of upmarket interior appointments usually found on Luxury versions of the Mazda6. These include leather seats, Bose sound system with seven speakers and a power-operated driver’s seat with three position memory.

The power operated driver’s seat position can be programmed into the car’s retractable keys allowing `his and hers’ settings to be recalled as you open the car door.

Like their petrol counterparts the Mazda6 Diesels, which will wear MZR-CD badges on each front door, boast impressive safety features. They have six airbags -- dual front, front side for driver and passenger and head protecting curtain airbags – and ABS anti-lock brakes with Electronic Brake-force Distribution.

Other safety items include a breakaway brake pedal to reduce possible foot, ankle and lower leg injury; anti-whiplash head restraints for the front seats while all three rear-seat passengers get a head restraints and a lap/sash seatbelt.

To ensure that cargo remains restrained at all times, the Mazda6 wagon comes with a roll-up net that fixes to the roof behind the rear seats, or from the floor to the roof when the second row seat has been folded flat.

Mazda Australia managing director, Doug Dickson, said: "The Mazda6 petrol range has enjoyed great sales success and critical acclaim. The addition of a state-of-the-art diesel hatch and wagon will ensure that it remains the country’s favourite medium segment import.

“Customer feedback from motor shows helped cement our plans to import a hatch and wagon diesel model, with these body styles proving to be popular choices. The hatch, with more than 50 per cent of petrol Mazda6 sales, continues to be the most popular body style, while adding a diesel to the wagon gives us a manual version in this body style for the first time.

“Fuel economy has become a hot topic of late and we expect it to remain an important consideration for car buyers. Offering the spacious, fun to drive Mazda6 with a fuel economy rating of just 5.9L/100km will give customers an opportunity to purchase a stylish, five-seat, safe and family car without performance compromise or fuel bill worries”.

Mazda Australia expects to sell at least 50 Mazda6 Diesels a month, with 30 of those likely to be the hatch.

2. Diesel Technology

The car’s MZR-CD 2.0-litre common-rail turbo diesel engine 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 Mazda6’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.

Advanced common-rail fuel injection

The MZR-CD engine’s common-rail fuel injection system injects fuel at an ultra-high 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.

Fuel atomisation is excellent, and fuel is injected in precise quantities in immediate response to running conditions. This substantially improves the engine’s combustion efficiency, to boost power and dramatically reduce NOx and particulate emissions.

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 cataylised 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.

These attributes combine with the tall gear ratios provided by the Mazda6 Diesel’s six-speed manual gearbox to produce not only 360Nm of torque but impressive fuel economy numbers.

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 Mazda6’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 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.

3. Mechanical Changes

Six speed manual shared with MPS models

The diesel engine mates to the same three-shaft gearbox first used in the Mazda6 MPS.

To handle the engine’s high torque and to ensure smooth gear changing, first, second and third gears feature triple cone synchronisers, fourth gear has a double cone synchroniser and fifth and sixth gears have a single cone synchroniser.

Suspension

The Mazda6 Diesel’s double wishbone front and multilink rear suspension only differs in spring rates (slightly firmer) compared with the petrol driven models.

4. Pricing

Mazda6 Diesel wagon $35,205

Mazda6 Diesel hatch $38,090

Photos of Mazda6 Diesel are available on autonews.net.au and autodeadline.com.au