Plastic-Intensive Vehicle Déjá vu?

Porsche's $440,795 Carrera GT road car has a carbon fiber monocoque, bodywork, and engine cradle. While the price and the material used are seemingly stratospheric for the average car buyer, the thought of building plastic-intensive vehicles in high volume is not as far-fetched as at first it might seem. However, the industry has had that dream before.

When Lotus introduced its Elite at the 1957 Earls Court Motor Show in England, it was the world's first plastic-intensive production car. Its fiberglass structure used local metal reinforcements for the engine and suspension mounts, hinges and door surrounds, but relied on the bonded two-piece monocoque for everything else. Many admired it, but no one adopted its construction method. Even Lotus dropped the Elite as it was too expensive to build, noisy, and difficult to manufacture. Will the Carrera GT lead to the same impossible dream?

It could if big gains aren't made in terms of reducing cost and manufacturing time. For example, the car's carbon fiber reinforced plastic (CFRP) engine cradle takes one week to build by hand. The pre-impregnated fibers (a.k.a. "pre-pregs") must be laser-cut and hand laid into a mold, vacuum bagged, and placed in an autoclave for curing. Volume production of a similar design will require a high level of automation, and quick cure times. Dr. Guan Chew, senior manager, Engineering and CAE, Porsche Engineering Services (Troy, MI) doesn't see this as an insurmountable hurdle, and suggests that this is one case where familiarity won't breed contempt. "We understand plastics so much better than we did in 1957," he says, "and have reached a point where we are becoming more comfortable with it in this industry. Once engineers have the necessary design and development tools, and can see what they can do with plastic, they'll use it more." 

In an attempt to educate the auto industry to the advantages of plastics, the American Plastics Council has created a technology roadmap built around four major elements: New Applications, Speed to Market, An Enabling Infrastructure, and Sustainability. Each is aimed at improving plastic's reach into interior and exterior applications, power systems (including fuel cells and hybrids), chassis and drivetrain applications, and–by 2015–resulting in the design and demonstration of a plastics-intensive vehicle and the manufacturing techniques that can be used to take it into volume production. For that vehicle, this will mean creating new alloys and polymer blends, thermosets with thermoplastic-like properties and manufacturing methods, new fiber reinforcement technology, pre-colored composites with a class-A surface, and more. "It's a tall order, but not an impossible one," says James Kolb, v.p. Automotive, American Plastics Council. Porsche's Dr. Chew agrees. It is this lack of knowledge that is hurting the adoption of plastic designs today.

"You can't take advantage of plastic's strengths if you use it in a material substitution fashion," he says. Chew should know. He can name countless cases where OEMs attempted to change a design from metal to plastic, none of which worked to anyone's satisfaction. In addition, he has spent an inordinate amount of time convincing OEMs that a well-researched and developed decision to go with plastic shouldn't be overturned. "All levels within the OEMs must understand that you have to start with the material in mind from the earliest stages, and look at the total systems cost. Otherwise, you'll convince yourself that it won't work, change direction, waste time and money, and never reap the benefits your initial analysis highlighted."