By David Sedgwick, Automotive News
Detroit, Michigan -- The US government's new corporate average fuel economy target has spurred automakers to launch a campaign to slash the weight of their vehicles.
There appears to be a growing consensus that vehicle weight must be reduced 10 to 15 percent to achieve the government's 54.5 mpg fuel economy standard, effective by the 2025 model year.
This month, research firm Ducker Worldwide of suburban Detroit issued a report that forecast vehicle weight reductions of 10 to 12 percent by 2025. Meanwhile, the Center for Automotive Research in Ann Arbor, Michigan., predicted vehicles would be up to 15 percent lighter.
A typical vehicle weighs about 3625 lb (1.6 tonnes), which means automakers will seek to eliminate 360 to 540 lb (163-255 kg), if industry estimates are correct.
At least one automaker, Ford Motor Co., has publicly vowed to reduce the weight of new models introduced through 2020 by 250 to 750 lb per vehicle.
It is most likely that automakers will achieve this by relying heavily on lighter materials -- such as aluminium, magnesium, composites and carbon fibre -- along with advanced high-strength steel.
Given the high cost of carbon fibre, automakers generally will make greatest use of aluminium and advanced high-strength steel, said Richard Schultz, a Ducker managing director.
"The real loser will be 'mild' steel, but so what?" Schultz said. "The steel mills see this conversion happening, so they are replacing their equipment."
This conversion to lighter materials will occur step by step, as automakers redesign hundreds of parts.
Most companies prefer an incremental approach rather than clean-sheet experiments such as Jaguar's primarily aluminium XJ sedan or the Audi A8's aluminium spaceframe, said CAR president Jay Baron.
Automakers are "risk averse, because making a mistake is so costly," Baron said.
But some ambitious experiments have been launched. The US Department of Energy has funded a $10- million effort by Chrysler Group to design a seven-passenger minivan that weighs half as much as a typical people mover.
Chrysler declined to discuss the project, but industry sources say the designers will make use of magnesium, aluminium and composite components.
Ford's efforts to cut weight means new models are starting to show the results. The new Explorer, for example, features an aluminium hood that is 17 lb lighter than a steel one. And a magnesium seat frame for the Explorer's third row saved 10 lb.
Another example: the Lincoln MKT crossover has a liftgate made with a magnesium inner panel plus an aluminum outer panel. The magnesium-aluminium liftgate weighs 87.5 lb, vs. 109.5 lb for a standard steel one.
The liftgate, developed jointly by Ford and Meridian Lightweight Technologies Inc. of Strathroy, Ontario, won a 2010 Automotive News PACE award.
Weight reductions such as these arguably are invisible to the motorist, who may not care whether his hood is aluminium or steel. But other efforts to cut weight may encounter consumer resistance.
For example, Magna International Inc., of Aurora, Ontario, developed a front seat called Futureform, a 39-pound product that weighs 20 percent less than a conventional unit.
Its thin seat back saves weight, and thinner contours allow rear-seat passengers more legroom. To hold costs down, Magna used high-strength steel -- twice as strong as conventional steel -- in the frame rather than pricier materials such as carbon fibre or magnesium.
But Magna doesn't have any contracts yet. Why not? Consumers perceive the seat to be less comfortable, admits Jim Rudberg, a seating engineer for Magna.
The supplier's own tests conclude that the new seat is just as comfortable. But participants in Magna's customer clinics insisted that the seats didn't look comfortable.
This problem first popped up a few years ago, when Magna developed the fold-down seats for Chrysler's minivans with Stow 'n Go seating. Consumers thought the fold-down seats looked too skinny -- hence uncomfortable -- so Magna had to fatten them up.
What will it cost?
While 10-year cost projections necessarily involve guesswork, industry analysts aren't that far apart. The Ducker report puts the cost of a 10-percent weight reduction at $500 per vehicle.
The CAR study estimates that a 15-percent weight reduction would cost $1,156 per vehicle.
Such estimates assume that automakers will gradually switch to new materials rather than make a one-time change to slash weight.
But some major innovations are in the works, too. At the Frankfurt auto show, BMW AG is unveiling the i3 electric car, an innovative vehicle made largely of carbon fibre.
In addition, Audi AG is unveiling a redesigned A2 with an aluminium body and spaceframe.
The Detroit 3 may be willing to experiment, too. Schultz of Ducker Worldwide hints that an American automaker plans to develop an aluminium-body vehicle in the next five to 10 years.
Likewise, rumours are circulating that an American automaker may develop a sports car with a carbon fibre monocoque, or unibody.
If successful, these projects could speed the pace of innovation. But automakers are unlikely to adopt exotic materials for mass market models regardless of cost.
If the price of a new part is more than 5 to 10 percent higher than the old part, said Magna's Rudberg: "We won't even bother."