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by Brett Davis

There are cars out there that will do the 0-100km/h sprint in less than seven seconds (easily quick enough to scare your mother) while returning fuel economy figures that hover around the 6.5L/100km mark. This is quite an astonishing feat, and manufacturers have been honing and engineering the combustion engine frantically for the past few years to further improve these figures. The latest focus on fuel efficiency in Japan, however, is shedding weight. Japanese car makers are now aiming to produce cars that are lighter than previous models and say this is the next step in providing customers with a fuel efficient package.

The only problem with this technique of keeping the planet cool is the reduction in safety a featherweight car provides. A spokenman from Suzuki Motor Corp. Takuma Mizuyoshi has said, “It is more difficult to maintain safety by reducing the weight.”

A lot of car makers are aware of this general rule, but they say by using stronger materials and adopting new safety technologies, a small, light-weight car can still remain safe. And it’s the small-car capital of the world, Japan, that is leading the way.

Honda, for one, says they are utilising the safety technology used in their very small cars and applying it to their weight-stripped larger cars. Koichi Kamiji, senior chief engineer for automobile safety at Honda R&D Co. says this is a great advantage for Honda.

In a world full of tightening emission regulations and increasing petrol prices, weight shedding could be the key to maintaining our resources. Japan began to realise the benefit of lightness a while ago. They have a category of car, known as the minicar, whereby engine sizes must remain under 660cc (0.66L) and the car itself must be no longer than 3.4 metres and no wider than 1.48 metres. This style of car has been the stepping stone for Japanese car makers, heading towards improved economy.

Honda says these types of cars still remain safe by using multiple frame rails that are made of lighter and relatively thin materials. The system, called Advanced Compatibility Engineering, is now applied to all Honda vehicles but it was first seen on the Honda Life in 2003.

Mazda Motor Corp. has also made weight loss the central focus of their design philosophy. They hope that by 2015 they will have increased their average fuel economy from 2005 by 30 percent. And they hope to do this by shedding 100 kilos from the latest generation of each model. We can already see evidence of this with the latest Mazda2, which has lost 43 kilos compared to the earlier 2003 models.

The use of lighter materials in the foundations of the car’s platform is the key. Carbon fibre, aluminium and high-tensile steel are both just as strong as traditional materials and much lighter as well.

Toyota has jumped on the weight-loss bandwagon too, and have been on it for around 10 years. Toyota began using ultra high-tensile steel in the framework of the bumper bars for their cars about 10 years ago. These were manufactured under more than double the pressure of ordinary steel manufacturing. Seigo Kuzumaki, project manager of Toyota vehicle safety says that it’s difficult to press complex shapes and curves using ultra high-tensile steel though, restricting the areas of the car this technology can be applied to.

Toyota has since found a way around this by adopting a technique called hot pressing. This simply means the high-tensile steel is preheated and can be formed and moulded much easier. The latest generation Prius has B-pillars formed using this method and the pillars are now stronger and much lighter than the non-preheated versions used in the previous model.

The focus is changing for manufacturers though, previously, a bigger car was better, so car makers simply tried to trim weight as the generations of each model become larger and larger. Nowadays, the drive is to make cars smaller as well as lighter, Kuzumaki says.

“For the past 20 years, if we reduced a car’s weight, the gain was usually used to make the car bigger. Now cars need to be smaller and lighter, so the pressure is increasing.”

Of course, there is limitations on what car makers can do, as Honda’s Kamiji says, “We always think about reducing weight, but realistically, there is only so much you can do.”




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