The new Mazda MX-5

Almost all new automobiles today are in danger of being heavier than their predecessors, due to ever-stricter safety standards and higher customer demands for comfort features. Mazda wanted to reverse this trend – and was successful.

Delivering a lightweight roadster had highest priority during the development of the new Mazda MX-5. As a result, the third-generation version of the cult roadster is only 10 kg heavier than its predecessor (depending on version). This modest weight gain is achieved despite the third-generation MX-5 being the first to have side airbags, despite having larger wheels, more powerful engines, an extended standard equipment package and a strengthened body shell.

Thanks to the gram strategy diet, the latest two-seater retains the true aura of Mazda’s original nimble, responsive handling roadster, a sports car whose rear-wheel drive transmission and powerful, frugal four-cylinder engines are still sufficient to deliver truly exhilarating performance. The soft top is still manual like before – so Mazda could avoid the heavier solution here of an electro-hydraulic retractable top.

By weight, 58 per cent of all body components of the new Mazda MX-5 are made of ultra high-strength steel or high-strength steel, which save 10 kg. Using aluminium for the bonnet, boot lid, the powerplant frame, front suspension control arms, rear hub carriers, rear brake callipers and rear suspension spring seats reduces weight even further. The front suspension control arms and the hollow front stabiliser alone cut 6.2 kg of unnecessary weight at the front axle.

Revolutionary Welding Process for the Boot Lid

Spot friction welding, a process first employed on the Mazda RX-8, is used for the boot lid of the new Mazda MX-5. This process, for which Mazda has registered 20 patents, joins zinc covered steel and aluminium panelling. Employing a high-speed spinning tool creates enough heat to spot bind these very different materials to one another.

The employment of zinc-coated steel sheeting has other advantages as well. Since zinc melts and runs when heated, it removes the oxidation surface that would otherwise remain at the spot the two metals are welded together, and only without this is a truly robust spot weld possible, because it prevents the chance of corrosion. This process also saves large amounts of electric current needed for traditional spot welding, and the boot lid is now 2.5 kg lighter as well.

Other examples of lightweight construction are the intake manifold (-2.4 kg) and the cylinder head cover (-1.3 kg), both being made of plastic. Mazda’s gram strategy also dictated mounting the power steering pump and the air conditioning compressor directly to the engine, which did away with the need of a bracket and saved 3.2 kg.

The engines themselves are also lighter than the engines of the outgoing model. The block of the 2.0-litre, for instance, is 5.4 kg lighter than the grey cast-iron block of the 1.8-litre power unit of the previous model.

Optimised Rearview Mirror Saves 84 Grams

Even the smallest of details like the rearview mirror contributed to Mazda’s painstaking vehicle diet programme. Simplifying the mirror’s design saved 84 grams. During the early phases of Mazda MX-5 development, engineers compiled a list of 573 weight-saving ideas. Had they incorporated all of these, the third-generation Mazda MX-5 would have been 43.5 kg lighter than the previous model. While this radical diet was not completely implemented for reasons of long-term durability and/or due to safety considerations, the kerb weight target for a new Mazda MX-5 entry-grade version was achieved.

Combined with perfect 50:50 weight distribution between the front and rear axles and a lower centre of gravity, the lightweight construction principle of the new Mazda MX-5 delivers high levels of driving fun and much improved occupant safety.

Through the use of high-strength steel, the body shell is now 47 per cent stiffer for torsional [twisting] rigidity and 22 percent for flexural [bending] rigidity – than the second-generation MX-5, an improvement that enhances both driving enjoyment and occupant safety.