Mazda in small-car three-peat

MAZDA’S redesigned global small car may wear a striking new set of steel clothes that aims to differentiate it from its popular bigger Mazda6 brother in the US, but underneath that stylish new look lies and a modified version of the original Mazda3’s chassis a new 2.5-litre engine that’s lifted directly from the Six.

But while the bigger, smoother and better performing new four-cylinder powerplant will be the headline act for Mazda Australia’s new SP25 range-topper, most of the engineering development work that went in to the BL-series model was focussed on the second-generation Mazda3’s revised platform.

In a similar approach that saw Volkswagen’s upcoming Golf VI based on the outgoing Golf V and in line with Mazda’s policy to completely renew its models only every second generation, the Mazda3 continues to share its fundamental chassis architecture with global Ford-family small cars including the Focus and Volvo’s C30, S40 and V50.

Left: Mazda3 program manager Yoshiyuki Maeda.

But Mazda says it has applied so many changes to the Blue Oval’s global C1 platform that it now labels it the C1-A, which was subsequently benchmarked against European small-car stand-outs including Audi’s similarly front-drive A3 and BMW’s rear-drive 1 Series.

“We didn’t seek to reinvent the car,” said Ruben Archilla, group manager of R&D at Mazda North America. “We didn’t see a need to change the fundamental concept, given the enormous success of a model that comprises 40 per cent of (US) volume and has increased its sales every year.”

Chassis development focussed on increasing rigidity “where it mattered” and reducing cabin noise, with both goals achieved primarily through more extensive use of high-tensile strength steel (590 mega-pascals or above, versus 270Mpa for standard mild steel, which is less than half as strong), which comprises 35 per cent of the new car compared with 18 per cent. The result is a claimed 11kg weight reduction for the new Three’s body-in-white.

Additionally, the front strut towers were reinforced and tied to the firewall, all suspension mounting points were beefed up, the sheet plate thickness of the front subframe is greater, the steering rack is now mounted at three rather than two points (and increases 1mm in diameter to 41mm) for better steering feel and the front anti-roll bar mounts are 20mm further apart for better roll control.

The instrument panel’s new two-tube support structure is 2kg lighter, while at the rear the suspension mounting point span is 15mm wider. There is also a larger front steering/suspension knuckle to reduce toe-out under suspension compression, resulting in a claimed reduction in understeer, while increased rear toe-in under bump is said to improve rear-end grip.

Damping rates at all four corners were revised, and the new Mazda3’s brakes are carried over but feature a retuned vacuum booster to improve initial brake feel.

While the entry-level 2.0-litre DOHC 16-valve four-cylinder petrol engine is largely carried over, US outputs of 110kW at 6500rpm and 183Nm of torque at 4500rpm are slightly up on the current 108kW/182Nm Australian-market unit.

The current Mazda3 diesel’s 2.0-litre turbo-diesel engine will be replaced within two months of the new Mazda3’s mid-year launch here by a new 2.2-litre turbo-diesel that offers 136kW and 400Nm in Europe and this week’s new Mazda6 diesel – but will offer only 110kW/360Nm in our Mazda3, representing only a 5kW improvement.

The new 2.5 has the same overall dimensions and bore spacings as the 2.3, but 30 per cent stronger aluminium castings and a new (as well as 1.5mm larger-diameter) molybdenum cylinder liner, new pistons and floating pins make it six per cent lighter than before. Relative to the Mazda6 engine, the Three’s 2.5 also has a more aggressive electronic throttle tune.

US output figures for the Mazda3’s new 2.5 are similar to that offered by the petrol Mazda6, at 124kW at 6000rpm and 227Nm at 4000rpm – compared to 115kW/203Nm for the outgoing 2.3-litre SP23.

The introduction of a five-speed automatic transmission in place of the old four-speed unit is claimed to result in a 10 per cent improvement in highway fuel economy thanks to its taller final drive ratio, and a six-speed manual will be standard across the range.

Europe’s new direct-injection engine with idle-stop technology won’t be sold in Australia due to our lower-quality petrol standards.

“What we decided to do was take what we’ve got… and set another new benchmark,” said Mazda3 program manager Yoshiyuki Maeda, who said the new Three’s development included more than one million kilometres of testing across 20 locations in 11 different countries.

“The first and biggest challenge was to develop a global car. The original car was a world-beater and I wanted to exceed customer expectations the world over, from Tokyo Sydney and London to LA.

“(It) offers a more expressive and dynamic design, improved performance in all areas and improved environmental and safety features. They also wanted excitement and value and the all-new Mazda3 delivers on all fronts,” said Maeda-san.

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