The '04 model year may be a turning point for aluminum in the auto industry.

After surpassing plastics in 2001 as third most-used material in the auto industry, behind steel and iron, aluminum rolls into '04 with two major breakthrough programs — the Jaguar XJ and BMW 5-Series.

The '04 models are two of the most aluminum-intensive, mainstream vehicles in automotive history, continuing an expansion trend that has seen aluminum use double on cars since 1991 and triple for SUVs, pickups and minivans in the same time period.

By 2010, vehicles will average 318 lbs. (144 kg) of aluminum, forecasts Ducker Research, up from the current 274 lbs. (124 kg).

Auto makers increasingly are using aluminum to improve fuel efficiency because it is lighter and stronger than conventional steel. For example, the seventh-generation XJ features an aluminum unibody that is 440 lbs. (200 kg) lighter than its predecessor, even though the new sedan is 4-ins. (10.2-cm) longer and wider, and 5-ins. (12.7-cm) taller.

Jaguar employed Alcan Inc.'s Aluminum Vehicle Technology (AVT) to design a stamped-sheet structure that is 40% lighter than an equivalent conventional steel body, and 60% stiffer than the previous XJ.

Additionally, the car's hood, doors, fenders, trunk lid, engine and suspension are aluminum.

XJ's major innovation is the adhesive bonding of structural-sheet sections in combination with self-piercing rivets — the U.K.-built car features almost no welds — similar to how aircraft are put together.

“For Alcan, the new XJ represents the culmination of two decades of automotive research and development, much of it in partnership with Jaguar (Cars),” says Travis Engen, Alcan president and CEO. “The launch of the car is as much a milestone for Alcan as it is for Jaguar.”

The redesigned '04 BMW 5-Series midsize sedan features an all-new aluminum chassis and front-end bodywork that replaces the outgoing model's steel framework. The front-end amounts to an aluminum space-frame, with all panels from the windshield pillars forward composed of aluminum.

The 5-Series' aluminum “nose cone” cuts more than 80 lbs. (36 kg) from the front end, permitting an even weight distribution between the front and rear axles, thereby improving handling characteristics.

Overall, lightweight technologies shaved anywhere from 121 lbs. (55 kg) to 143 lbs. (65 kg), depending on the model, from the 5-Series' curb weight vs. its predecessor, despite its larger proportions — nearly 2 ins. (5.1 cm) in every direction.

Mazda Motor Corp. also advanced aluminum automotive technology by becoming the first auto manufacturer to apply friction stir welding (FSW) to the manufacture of aluminum body assemblies. Mazda is using FSW for the rear doors and hood of its '04 RX-8.

Traditionally, “resistance welding” has been the most feasible joining technology available for assembling aluminum body parts. However, resistance welding requires a large amount of electricity and specialized equipment.

Mazda's joining method uses friction to soften the aluminum and generate plastic flow to join the parts. The auto maker predicts that its breakthrough use of the technology will have a dramatic impact on the possibilities for aluminum's use in automobiles.

Besides the XJ, 5-Series and RX-8, there are other new aluminum applications in the auto industry on the way. Highlights include:

  • Ford Motor Co.'s '05 GT features a spaceframe, engine, suspension and many other components made from aluminum.
  • Several vehicles are making the move to aluminum hoods, including the Mercedes E-Class wagon, Subaru Impreza WRX STi, Cadillac SRX, Nissan Maxima, Ford F-150, BMW M3 CSL and Mazda RX-8. Perhaps the most notable among these is the RX-8, which boasts a new impact-absorbing shock cone designed to enhance pedestrian protection. The hood boasts an inner panel that is specially shaped with numerous craters to manage impact absorption evenly across the entire surface of the hood. Mazda says severity of head injuries is reduced by 50% compared to a conventional hood. Thickness of the inner panel is reduced 22% and it's 1.5 times stiffer than traditional hoods.
  • General Motors Corp.'s '04 Chevy Malibu Maxx features an aluminum liftgate.
  • Chrysler Group's Pacifica features a 3.5L V-6 engine with aluminum cylinder block and head castings.
  • Ford's forthcoming Five Hundred sedan, Freestyle crossover and Montego sedan are expected to have aluminum V-6 engines, wheels, transmission cases and valve bodies, according to American Metal Market.
  • GM's 3.4L V-6 engine, to be used in the '05 Chevy Equinox, features aluminum cylinder heads.
  • Aluminum continues to grab suspension applications from steel, especially control arms, to better reduce “unsprung mass,” which is the weight of the components that move up and down in response to bumps in the road. Some notable aluminum control arm applications for '04 models include, the F-150, Cadillac XLR and SRX, Subaru Impreza WRX-STi and Chevy Malibu.
  • Aluminum windshield frame assemblies are expected to be used for the forthcoming next-generation Corvette, reports say.
  • The '04 Nissan Maxima and Mercedes E-Class wagon feature aluminum decklids.
  • Alcan will open a plant in Novi, MI, next year that will supply four unspecificed U.S.-built vehicles with aluminum bumpers.