The chassis for the second generation of the Mazda2 is based on a newly-developed platform that underscores the company’s long years of experience engineering small vehicles. In contrast to the Mazda2 introduced in 2002 which prioritised practicality, for new Mazda2 interior space became a shared priority along with delivering a more contemporary design and the same Zoom-Zoom driving fun as the other members of the modern Mazda family.

With a new state-of-the-art chassis as a foundation, Mazda engineers sought to provide outstanding handling for a car of this class, combined with high stability even on motorways and a harmonious ride quality. The low weight and high rigidity of the body shell played an important role in optimising handling and comfort. For handling, Mazda focused on manoeuvrability and agility on city streets, on steering that is spontaneous and linear, on achieving high grip on curving country roads and well-tempered reactions during fast lane-changing on the motorway.

An ingenious plan to reduce vehicle weight by around 10 percent compared to the former model was seen as the most ef?cient way to lower fuel consumption and CO 2 emissions . At a very early stage in development, a special team began looking for the best diet plan using advanced computer aided design or CAD technologies. After that, the engineers tested the ideas in drivable prototypes – initially in the previous Mazda2 – and examined the effects they had on the dynamic qualities of the car.

Their efforts were successful; once again, as it had done with the MX-5 roadster, Mazda was able to resist the spiral of ever increasing weight . An increased use of high-tensile steels led to a weight reduction of nearly 100 kg (depending on model). As a result, the new Mazda2 with the 1.3-litre petrol engine weighs considerably less than a ton – 955 kg. But Mazda2’s trend-bucking character is also evident by its length, which is now 40 mm shorter, at 3885 mm.

Use of High-Tensile Steels Has Several Positive Effects
Thanks to the optimised structure of its body shell and an increased use of new kinds of steel, the new Mazda2 is not only 10 percent lighter, but also improved when it comes to safety, body shell rigidity and NVH performance – all attributes that normally add weight to a car.
Through smaller dimensions alone, the weight of the body shell would have been cut by only 4 kg, to 233 kg. Measures taken to increase rigidity and crash resistance would have quickly raised it again to 244 kg. Thanks to the altered body structure and new materials, the team under the leadership of Program Manager Shigeo Mizuno was able to decrease weight to 215 kg – 22 kg less than the old Mazda2 body shell .

Up to 20 Percent Stiffer for Torsional Rigidity
The use of high- and ultra-high-tensile steels contributed ?rst and foremost to a reduction in body shell weight. For example, the B-pillars are made of 980 MPa-grade steel sheet (MPa = measurement of tensile strength). They act as central support columns and extend in the form of a ‘roll- over bar’ into the roof. Despite stronger joint reinforcements in the area of the door openings and the tailgate, the use of high-tensile steel with reduced thickness resulted in a weight saving of 6 kg. At the same time, torsional rigidity was increased . By employing additional spot welds and adding new weld-bonded joints in the tailgate opening of the new Mazda2, it is 20 percent stiffer than the square-edged hatch opening of the outgoing model.

Mazda weight specialists were able to save an impressive 13 kg using weight optimising measures in the suspension . These included making the rear trailing arms shorter and the front lower arms lighter. This reduction in unsprung weight promotes better handling and ride comfort, as well as enhanced fuel economy. But Mazda engineers did not stop there. They also eliminated the under?oor catalyst and – for the 1.3-litre engine – the presilencer. For the intake system, Mazda engineers modi?ed the intake duct design to the top of the radiator shroud. This new intake system eliminated the resonator and a baf?e, which also saved valuable weight, as did ?tting a smaller radiator and fan for the cooling system.

Weight-Saving Measures on the new Mazda2

Body Shell
Smaller dimensions alone would have lowered the weight of the body shell by 4 kg, to 233 kg. Measures needed to increase rigidity and crash resistance would have then raised it up to 244 kg. But thanks to an optimised body structure, weight was reduced to 215 kg, 22 kg less than the old Mazda2.

Intake and Cooling Systems
For the intake system, Mazda engineers moved the fresh air inlet from its original position behind the left headlamp to the top of the radiator shroud. This new position removed the need for the resonator and baf?e.

Bonnet
With a smaller striker assembly and thinner hinges, the bonnet saved 0.69 kg.

Suspension
Mazda weight specialists were able to save an impressive 13 kg using weight optimising measures in the suspension. These included making the trailing arm on the rear axle shorter and giving the front lower arms an open-section structure. This reduction in unsprung weight means both better handling and ride comfort.

Exhaust System
Mazda eliminated the underfoot catalyst, and for the 1.3-litre petrol model, the presilencer used in the Mazda2 until now was also eliminated.

Electrical System
A shorter wiring harness saved a total of 2.86 kg – achieved by an insightful placement of large units and power-supply parts.

Door-Mounted Speakers
Mazda’s weight watchers were also at work with the door-mounted speakers. By changing the magnets from a ferrite type to neodymium, and making the plastic moulding single-piece, a total weight savings of 0.98 kg was achieved.

High-tensile steel
The use of high and ultra-high tensile steel alone saved 22 kg. The 980 MPa- grade steel used in the area of the B-pillar is a kind of central beam for the passenger cell. Strengthened joint  reinforcements in the doors and liftgate saved 6 kg, without having to use thicker material.

Shortened Wiring Harness Saved 2.86 kg
The Mazda2 calorie-cutting team even found ways to reduce weight in the vehicle electrical system: a shorter wiring harness saved a total of 2.86 kg. What sounds like sorcery is in fact the result of an insightful placement of large units and power-supply parts. The bonnet also contributed to a weight saving of exactly 0.69 kg, with a smaller striker assembly and slightly thinner hinges. Even the audio speakers mounted in the doors were engineered to be lightweight: by changing the magnets from a ferrite type to neodymium, and making the frame and protective cover a single-piece plastic moulding, a total weight saving of 0.98 kg was achieved.

Acclaimed Suspension Concept Modi?ed and Retuned
The front MacPherson strut suspension and the torsion- beam rear suspension also pro?ted from the use of high- tensile steels in certain areas of the body shell to increase local stiffness and ensure optimal suspension geometry. The suspension system uses the same basic concept as that of the previous model, but the components have been modi?ed in many details and retuned to match the much more agile attributes of the new Mazda2. For example, Mazda made the suspension mounts at the axles 15 per cent stiffer compared to the outgoing model. In the front suspension, new bushes on the A-arms reduce road surface in?uences on the toe angle, which has a positive effect on ride comfort and improves handling stability and the integrity of steering feel.

The trailing arm bushes of the rear suspension are now less sensitive to side forces. The rear monotube dampers have the same diameter as before, but because of the lower vehicle weight they now are as effective as larger-diameter dampers.

Electric Power Assist Steering Supports Driving Fun
Mazda2’s electric power assist steering system is appealing for its very linear and direct response and supports the Mazda goal of oneness between driver and car – the philosophy of Jinba Ittai so completely embodied by the Mazda MX-5. This new steering system provides very high levels of power assistance when the vehicle is being driven at very low speeds, which is especially handy when manoeuvring in tight spots and parking. With only 2.7 turns lock-to-lock , the steering system is very direct. Together with a small turning circle of only 9.8 metre s, this makes the Mazda2 an ideal urban vehicle.

The brake system of the Mazda2 includes an Anti-lock Braking System (ABS), Electronic Brake-force Distribution (EBD), as well as Emergency Brake Assist (EBA) and ventilated front disc brakes. In order to improve pedal feel, the pedal ratio was lowered from 3.79 to 2.85, which means less play in the pedal stroke and a more de?ned response. At the same time, Mazda reduced the diameter of the master cylinder from 23.8 mm to 20.6 mm and optimised brake booster characteristics. By improving the brake piston seal structure, the drag that results from friction between the pads and the discs of the front brakes was signi?cantly reduced. Dynamic Stability Control (DSC) and Traction Control System (TCS) are also available (depending on market and model).

Testing in Europe

Engineers from the Mazda’s European development centre in Oberursel near Frankfurt, Germany gave the new Mazda2’s chassis a speci?cally European assessment on the meandering roads of Germany’s mountain region.

Alexander Fritsche, Team Leader Chassis/Suspension in Oberursel, says, “Our testing areas feature all conceivable kinds of curves and surfaces – ideal for us testers and the Autobahns there are ideal too, with relatively little traf?c.” Together with suppliers, Mazda engineers conducted extensive tests that not only identi?ed the most harmonious damper settings, but also the ideal characteristics for the electric power assist steering. “This system is speed dependent – a lot of assistance when manoeuvring at parking speeds and driving around town, less when driving fast,” Fritsche says. “For this reason it was important for us to always have suf?cient road feedback in the city and to tune the steering to be both sporty and comfortable as speed increases.”

Mazda not only made a quantum leap when it comes to steering feel and response compared to the outgoing model, but also for driving comfort and NVH. “We wanted to get away from the typically slightly harsh, B-segment feel and to signi?cantly increase the sense of ride comfort,” says Fritsche in outlining the goal of his team.

New pancake-type bushes are introduced for the lower arms of the front suspension, which are better at isolating the steering from exterior in?uences. The trailing arm bushes of the rear suspension are also better at smoothing out bumps and the geometry is designed to reduce roll and dive. “Europe usually represents the biggest challenge for Mazda’s development engineers when it comes to driving comfort. I’m con?dent that the new Mazda2 is impressive proof of just how consistently those challenges have been met,” concludes Fritsche.

Three-way Load Path Keeps Body Deformation Away From Occupants
Mazda2’s passive safety package is based on a body shell developed using the highly capable Mazda Advanced Impact Distribution and Absorption System (MAIDAS), which is able to disperse impact energy through the body shell along exactly de?ned load paths. In order to better absorb the energy from a frontal crash, the front side chassis members are straighter and have a larger cross-section.

An ultra-high- strength structure in the front bumper and a straight main underbody load path provide effective occupant protection. During an offset crash, a three-way load path de?ects impact energy away from the feet and lower legs of the front occupants. And the brake pedal is designed to collapse down and away from the driver’s feet.

Two Impact Beams in the Front Doors Provide Side Protection
During a side impact , B-pillars made of 980 MPa-grade steel, specially strengthened side sills and ?oor pan cross members provide effective occupant protection. In the front doors there are two side impact beams, which help protect occupants from injury, while a single beam in each rear door limits intrusion. Additional protection from injury is provided by shock-absorbing pads in the door trims, pillars and roof side rails.

In case of a rear impact , the back Seat passengers and the fuel tank (located below the cabin ?oor and directly in front of the rear axle) are given increased protection by a large rear bumper beam and new side members, which are also straighter than the old model and are made of 590 MPa-grade steel.

This crash-resistant survival cell of the Mazda2 is enhanced by two front airbags and seatbelts with pretensioners and load-limiters . Front side airbags and curtain airbags , for helping protect all occupants sitting in the outer seats, are either standard or optional (depending on grade and market). Pedestrian safety is also optimised by the special design of the bonnet, fenders and windscreen wipers.

High-tensile Steel
The use of high-tensile steel materials provides a solution to the seemingly contradictory goal of providing low weight and high crash resistance . By using higher tensile steel, the thickness of the steel sheeting can be reduced , while still retaining the desired body shell strength and structural characteristics. This saves weight and costs, while simultaneously increasing safety levels for the occupants.

For the body shell of the Mazda2, high-tensile and ultra-high-tensile steels with strengths of 440, 590, 780 and 980 MPa (mega-Pascal) are used. Varying degrees of strength are obtained through speci?c chemical and baking processes. Especially strong kinds of steel are used for the A- and B-pillars and the front door sills. Together with an increased number of spot welds – especially in the door openings and the side walls of the boot – this gives the Mazda2 a survival cell that truly deserves the name.

How resistant are the special steels?
Imagine a metal bar with a 3.5mm diameter, its critical failure point clearly varies depending on its type (high tensile / ultra-high tensile)…

Note: if the metal bar diameter was 11.18 mm, the load to tear it would need to be 10 times higher (x10)

Environmentally Friendly Production Methods
Besides making the interior surfaces nice to touch and providing the best ergonomics, the creators of the new Mazda2 also were keen to make sure the cabin does not release unhealthy substances into the air. The design team’s special focus concerned volatile organic substances (VOCs). An example of their efforts to cut VOCs was the reduction of toluene.

For the? First time, Mazda used a new substance for waterproof sealing the joints between interior panels, which gives off only one tenth of the emissions previously emitted by conventional sealers. By adopting this new subsance, the total concentration of toluene has been reduced by around 60 percent compared to the outgoing model. And not only that, the amount of xylene, formaldehyde, acetoaldehyde and polyvinyl chloride has been signi?cantly lowered. Lead, cadmium, Mercury and chromium were banned completely from the Mazda2.

Mazda2’s environmentally friendly character is also evident by its high recyclability. The new Japanese sub-compact meets the ISO 22628 norm and is more than 95 per cent recyclable . The bumpers, for instance, are made of a material that can be recycled into foot rests and splash.