THE Mazda3 range has been joined by a new diesel model that costs less and delivers more power and torque than before as well as producing the best fuel figures of any Mazda on the local pricelist.

Mazda expects to sell about 100 Mazda3 Diesels a month into market niche which it says has levelled out at 7.4 per cent of small-car sales after growing strongly for five years.

And it admits it could probably do more, except for the lack of an optional automatic transmission.

Mazda Australia boss Doug Dickson said that while the numbers expected for Mazda3 Diesel are relatively small, he believes the diesel market will become increasingly important as oil prices rise.

He said he believed it was important to be part of that market now, despite not having the auto option.

The previous Mazda3 diesel, of which about 1100 were sold, was introduced in 2007, but when the new 3 arrived in April this year, the diesel was absent from the price list because Mazda believed it would not be profitable in the new range.

Since then, the exchange rate has become more favourable, tempting Mazda to give the diesel the go-ahead.

At $29,715, the new Mazda3 Diesel is $685 cheaper than the previous model, although it commands a $2870 premium over the Maxx Sport on which it is based.

Mazda believes the new model will only account for five per cent of total Mazda3 sales, split roughly 50-50 between sedan and hatch. The sales numbers are not particularly high, partly because the Mazda3 Diesel is not available with an automatic transmission.

The diesel 3 was engineered primarily for Europe, where low take up of automatic transmission – just 8.1 per cent for the first eight months of 2009 across the industry – did not warrant the optional gear changer.

While Australian registration figures do not split the figures according to transmission, in the case of the Mazda3 petrol models, Mazda says that sales are running about 55-60 per cent in favour of the automatic.

The Mazda3 Diesel is fitted with the same MZR-CD 2.2-litre common-rail inline four-cylinder turbo-diesel as fitted to the Mazda6, although in the new Mazda3 Diesel, a smaller variable-geometry turbocharger is used.

Outputs are 110kW of power at 3500rpm and 360Nm of torque at 1800rpm. That is up 5kW on the 2.0-litre MZR-CD in the previous Mazda3 Diesel, which shares the same maximum torque output but it is now developed 200rpm lower in the rev range.

Aside from increasing displacement from 2.0 to 2.2 litres, other changes to the MZR-CD engine include longer and more streamlined turbo blades, increased fuel pressure from 180Mpa to 200Mpa, new solenoids to speed up the fuel injection intervals by 30 per cent and 20 per cent smaller fuel injectors that now have 10 holes – up from six.

New pistons are said to cope better with the rigours of combustion, and feature a design that improves carbon emissions performance. Compression ratio has been lowered, and an improved DPF filter fitted.

Despite the larger displacement, engine weight is up just 6kg over the previous engine while overall dimensions are similar.

The six-speed manual transmission has been revised for improved shifting and has different in-gear and final drive ratios to the petrol models.

The improvements net a 1.7-second reduction in acceleration time from 50km/h to 100km/h, while combined fuel consumption is down from 6.0L/100km to 5.7L/100km and emissions are down from 160g/km to 150g/km.

Kerb weight is 1438kg for sedan and 1456kg for the hatch, which is up from 1405kg and 1425kg respectively over the previous diesel 3.

The new diesel trim level is based the Maxx Sport in the petrol 3 range, so standard equipment includes 16-inch alloy wheels, front fog lights, power windows and mirrors, air-conditioning, cruise control, leather gearshift knob and steering wheel, trip computer, Bluetooth (hands-free compatible), maintenance monitor, satellite-navigation, a MP3/WMA-compatible in-dash six-disc CD player with six speakers and auxiliary input, and steering wheel-mounted audio controls.

Standard safety features in the Mazda3 Diesel include ESC, traction control, ABS, electronic brake-force distribution, emergency brake assist, active front head restraints and front, side and curtain airbags.

New exterior colours to the Mazda3 Diesel range include Celestial Blue, Indigo Lights, Aluminium, Gunmetal Blue and Graphite, as well as the already available Crystal While Pearl, Gunmetal Blue, Velocity Red and Black, while the interior is black cloth only.