Lightweight Structures in Limelight - Vehicles may get lighter even withoutmandates

So what really is more important about Miller Lite beer - the fact that it is "less filling" or "tastes great?" Judging by current vehicle sales in the U.S., more Americans spend time worrying about this old advertising slogan than they do about fuel economy or the great global warming debate.

With gasoline prices barely above $1 per gallon, giant sport/utility vehicles (SUVs) weighing more than 5,000 lbs. (2,270 kg) are flying out of dealer showrooms at full sticker price, while thrifty subcompacts weighing half as much - such as the Dodge Neon - aren't selling, despite big incentives. And when given the choice between less-expensive, more fuel-efficient V-6 engines in pickup trucks and SUVs, more than ever, Americans are opting for more powerful and thirsty V-8s.

Despite this utter lack of interest in fuel economy in the U.S., a lot of money and effort are being invested in lighter vehicle bodies. They aren't just cynical public relations programs, either. The aluminum industry has targeted aluminum body structures in the transportation industry as a key new growth area as opportunities in mature markets such as aluminum cans and aerospace dwindle.

The steel industry sees the challenge from aluminum and is responding by developing lighter-weight car and truck bodies that - while not as light as aluminum - weigh significantly less than traditional steel bodies and cost less to boot. The upshot: vehicles eventually may start to get lighter even without government mandates or marketplace demand thanks to inter-materials competition and the fact that gasoline costs $3 to $5 per gallon in most of the world's major car markets.

The Big Three U.S. automakers made a splash at the North American International Auto Show in January showing off each of their high-mileage vehicles that featured lightweight bodies developed as part of the four-year-old Partnership for New Generation of Vehicles program. But other independently developed lightweight vehicle bodies and technologies are emerging as well.

Drowned out by the Big Three's environmental drum beating at NAIAS, for instance, was an interesting concept car by Wilhelm Karmann GmbH, featuring foamed aluminum panels. The panels consist of a sandwich of sheet aluminum and a core of aluminum "foam." Unlike other composite metallic materials such as aluminum honeycomb, it can be used to produce stamped complex-shaped sheet-metal structural parts. These parts are up to 50% lighter and 10 times stiffer than conventional steel parts, Karmann says.

"Until now, no one in the automotive industry had been able to perfect a lightweight composite sheet metal process so that it is economical and practical for application to low-volume automobile production. Our process overcomes the major inherent disadvantages of traditional materials, such as conventional aluminum honeycomb," says Dr. Wolfgang Thurow, vice president of technical development-sales and marketing at Karmann.

Sandwich panels and aluminum foam have been around since the 1950s, Mr. Thurow says, but until the Karmann-patented process was developed, no one had managed to adapt the technology to sheets that could be formed into the complex shapes needed for automobiles. As much as 20% of the typical automobile's structure could contain aluminum foam panels, and that could lead to a weight savings of 133 lbs. (60 kg), he says.

Not willing to be upstaged by aluminum for long, the steel industry is poised to introduce real live versions of its UltraLight Steel Auto Body in early March. The unveiling of the ULSAB is the culmination of a three-year, $22- million design and validation project to demonstrate that steel still is the best material for future auto structures. A consortium of 35 of the world's largest steel companies funded and managed the project.

Engineered by Porsche Engineering Services Inc., the ULSAB is expected to weigh 35% less than a conventional steel body-in-white, have significantly better engineering properties and cost about $150 less. Eleven prototypes are expected to be produced by Porsche Engineering to be distributed among consortium members to show customers and the media. A light truck ULSAB also is in development.