Just how badly do we need to reduce weight? This is the perennial question automotive engineers ask when evaluating magnesium applications.

The ultra-lightweight metal is making steady progress. Byron B. Clow, executive vice president of the International Magnesium Assn. says that in North America alone magnesium components used by automakers have jumped from 33 in 1991 to 162 in 1997. American Metal Market predicts magnesium use in 1999 models will rise 8% from 1998, to about 7 lbs. (3 kg) per vehicle.

Compared with other materials that account for hundreds - or thousands - of pounds per vehicle, magnesium may seem almost insignificant. But its rise from 1 lb. (0.45 kg) in a typical family vehicle 20 years ago to an estimated 8.7 lbs. (4 kg) in a similar car for model year 2000 makes it one of the auto industry's fastest growing materials.

There are two main reasons why it has increasingly gained favor with automotive planners, designers and engineers: formability and weight reduction.

Although the raw product is more expensive than steel or aluminum (magnesium die castings are about $1/lb. more than even costly aluminum) the price of magnesium on world markets has been dropping.

Early this year, influenced by Russian and Chinese production, prices reportedly dipped almost 20%.

Over the past several years, the need to keep ahead of mounting pressures for improved fuel economy has prompted automakers to examine magnesium more closely.

The Big Three have been especially active, according to Hydro Magnesium, a division of Norway-based Norsk Hydro AS. Applications include steering wheels, steering column brackets and retainers, alternator brackets, headlight retainers, ABS mounting brackets, transfer cases, air bag housings, electronic housings, valve covers, sunroof assemblies and instrument panel (I/P) cross-car supports.

Hydro Magnesium has been working with automakers worldwide in advanced product design to develop further applications for seat brackets, door frames and front-end grille opening reinforcements, the latter already in production on the Audi A8 and BMW 7 series.

Two new applications involve the Mercedes-Benz SLK convertible: a magnesium fuel tank cover and retractable roof components. Other applications coming include underbody structural components, transmission cases, oil pans and valve covers.

But cost-conscious Ford Motor Co. has slowed magnesium's growth by switching several high-volume applications - most notably 4-wheel-drive transfer cases - back to less-costly aluminum. Fortunately for magnesium, General Motors Corp. made the opposite decision. The transfer cases on its new GMT800 pickup trucks are magnesium. - with Drew Winter