GENEVA - Carmakers cut weight and increased body stiffness on several models which debuted here by using high-strength steel, laser-welded blanks and other technologies.
Steel replaces aluminum for door panels and the hood and trunk on Rolls-Royce's new Silver Seraph. Rolls claims a 60 percent increase in body rigidity.
Rolls also saved weight by replacing the full-sized spare wheel with a mini spare made of titanium.
BMW cut the weight of the new 3 series chassis by 8kg by using for the first time laser-welded blanks and hydroformed rear-suspension parts.
High strength steel now accounts for half of all steel in the car. The result is a 60 percent increase in body stiffness, BMW said.
Magnesium is used for such parts as the oil pump. But Wolfgang Ziebart, 3 series product manager, said, 'We do not say that it is the material of the future.'
Other 3-series innovations:
The airbag control unit automatically disconnects the battery cable in an accident to prevent sparks that could ignite fuel.
Electronics replace mechanical switches for light bulbs, so that if one bulb blows other bulbs compensate with increased brightness.
Free-form reflectors developed by Bosch replace parabolic reflectors in the headlights, so that clear glass covers can be used. Xenon bulbs are offered as an option for the first time.
A controller detects when air quality is lower inside the car than outside and automatically starts air circulation.
The fit of body panels is measured on the production line by lasers. They test the accuracy of 130 points on the bodyshell to +/-0.1mm.
Stiffer bodies and lower weight were also achieved on the new Ford Focus and General Motors' Astra by using magnesium, hydroformed components, laser-welded blanks and high-strength steel.
Cutting the weight of the new Astra by 145kg increased costs by DM250 per vehicle, said Herbert Heil, Astra platform director.
Adding new features offset the weight savings, he said.
Both the Focus and Astra will use laser measuring of bodyshells as the cars travel down the welding lines.