Aluminum's Allure

Despite lean times for North American auto makers, the use of lightweight aluminum in vehicles shows little sign of letting up, says Tom Gannon, chairman of the Aluminum Assn. Inc.'s (AAI) auto and light truck group.

By 2008, Gannon predicts the amount of aluminum in North American vehicles, currently about 280 lbs. (127 kg), will continue to rise 2.5%-3.5% annually and ultimately will replace iron as the second most used material in automotive production behind steel.

Japanese auto makers are expected to drive much of aluminum's future growth as they become more comfortable with using the light metal, Gannon says.

Although Japanese auto companies manufacture lots of aluminum engines and suspension components, and certain Japanese vehicles — such as the aging Acura NSX — feature aluminum-intensive bodies, Japanese auto makers in general have been slow to embrace the material for body panels and structural applications.

“They move slowly and pick their opportunities,” Gannon says. “They take it to the next level incrementally.”

A perfect example is the Toyota Prius. Despite its innovative hybrid electric powertrain, the first generation Prius had a very conventional steel body. The current generation adopted aluminum for its liftgate hatch.

The '05 Subaru Legacy wagon also features a lightweight aluminum liftgate.

Europe, a long-standing bastion of aluminum applications in automobiles, will continue to exploit aluminum's benefits, Gannon says. From the aluminum-intensive Audi A8 and Jaguar XJ to the aluminum front end of the current BMW 5-Series and Audi A6, European auto makers have used the lightweight metal to maximize performance and fuel economy in their home markets, where fuel prices still are 2-3 times that of the U.S.

Aluminum front-end structural assemblies also are helping European and some Japanese auto makers, such as Mazda Motor Corp., to meet strict pedestrian collision safety standards, while still keeping vehicle weight in check.

A new study by the Dynamic Research Institute (DRI) also suggests aluminum could be used to make SUVs safer in crashes with other vehicles.

Gannon says aluminum allows engineers to create a more favorable weight balance in vehicles, a concept that traditionally has been of higher value in Europe than in the U.S due to the region's high-quality roads and European drivers' preference for cornering ability and high-tech cars.

BMW AG's use of aluminum for the front suspension, substructure, hood, fenders and other panels of the current 5-Series, along with the use of traditional steel for the back half of the car, help the midsize sedan attain a near perfect 50/50 weight balance between front and back — a most desirable trait for an auto maker that touts producing the “Ultimate Driving Machine.”

North American applications of aluminum also have increased in recent years as evidenced by the aluminum hoods and/or decklids on the '05 Chrysler 300 and Pacifica, Dodge Magnum, and the Ford Mustang, Five Hundred and Freestyle, just to name a few.

General Motors Corp., the world's largest auto maker and North America's biggest player in automotive aluminum applications with more than 300 lbs. (136 kg) of aluminum per vehicle, according to AAI's last study, also is reducing the aluminum content of a number of key high-volume vehicles in favor of cheaper high-strength steels — at least for several model years.

GM's decision to use a steel liftgate design on its next generation of fullsize SUVs, in place of the aluminum unit found on current models was a big disappointment to the aluminum industry, Gannon says.

Nevertheless he is hopeful new applications can be found that can help replace that loss, he says.