Thanks to the growing emphasis on modules, instrument panels with structural plastic innards are winning acceptance on some high-volume car programs after a long trial period. Sources say General Motors Corp. plans to use structural plastic IPs for its upcoming Delta Program small cars. It also is evaluating them for its larger Epsilon program vehicles, which include midsize sedans such as the 2004 model year Chevrolet Malibu. The high-tech plastic IPs already are well established on DaimlerChrysler light trucks such as the Dodge Dakota and Durango and the Chrysler Cherokee and Grand Cherokee. Insiders say they'll likely show up on next-generation versions of Cherokee and Grand Cherokee as well.

For decades plastic has been used for the exterior parts of IPs that face the driver and passenger. But look inside and you'll see big support beams or tubes made of metal. These steel, aluminum or magnesium reinforcements give IPs the strength and stiffness needed to withstand crashes, serve as a platform for deploying air bags and prevent squeaks and rattles. The new IPs consist of two large injection-molded plastic parts that are welded together ultrasonically to form a very strong structural component. A hollow plastic cross-car structural beam is an integral part of the molding and also serves as an air duct for the IP heating, ventilation and air conditioning system.

Major plastics producers and interior system suppliers have been developing such concepts for at least 10 years, including Dow Automotive, GE Plastics and Exxon Chemical Co., but they have seen only limited success. Dow Automotive won the first application (the IP on the now-discontinued Buick Roadmaster in 1994) and is believed to be the only company whose concepts currently are in production. It will provide the plastic for the upcoming Delta Program IP system, which will be supplied by United Technologies Automotive. Recently purchased by Lear Corp., UTA won the giant contract to supply the fully assembled IPs to General Motors. Analysts estimate the deal is worth between $400 million and $500 million.

GE Plastics is trying to sell GM on the idea of using structural plastic IPs on Epsilon vehicles, which is a GM program for midsize sedans farther out on the horizon than Delta. Although GE doesn't have any totally plastic structural IPs in production, Ford Motor Co. is using an IP incorporating a GE-supplied structural thermoplastic air duct on the current Lincoln Continental, says Amanda M. Butler, GE's Market Development Manager-IP Systems. Ford also has experimented with thermoset sheet molding composite (SMC) plastic for cross-vehicle beams on several light truck models.

The selling points for structural plastic IPs are lower costs and lower weight. John Zessin, Commercial Director for Dow Automotive says the all-plastic IP on the Dodge Durango saves 10 lbs. (4.5 kg) and $10 per truck. While every vehicle is different, structural IPs can yield savings in the same ballpark for other cars and trucks, he says, although he won't comment on the Delta program.

Using just a thermoplastic air duct in the Continental saved Ford $5 and 5 lbs. (2.2 kg) GE says.

So-called integrated structural IPs save automakers money by consolidating dozens of small metal and plastic parts into just a few big plastic parts. That eliminates costly assembly steps and labor. It also makes the IPs easier to disassemble and recycle, because they're all one single type of plastic material, proponents argue.

Nevertheless, suppliers acknowledge the technology poses some difficulties as well. Designing modular assemblies that consolidate numerous parts is difficult, especially when they must bear substantial loads and forces. The expansion and contraction of big plastic parts over wide temperature ranges also pose some challenges for engineers, suppliers say.

The news that GM is adopting this technology for its Delta program is more evidence the automaker is serious about cutting costs via modularization on its new line of small cars that are slated to be part of its innovative Yellowstone program.

GM says it currently loses about $1,000 on every small car it now builds. The Yellowstone program aims to eliminate those losses by replacing aging small car plants in areas such as Lansing, MI, and Lordstown, OH, with new greenfield plants and the latest modular manufacturing techniques to dramatically improve margins on finished vehicles.

The Delta car program will encompass nearly all compact and subcompact cars in GM's global portfolio, including the next generation Chevrolet Cavalier, Pontiac Sunfire and Opel Astra. Together the potential volume could be more than 1 million vehicles per year, although Opel versions may not use the technology, sources say.

However, Jim Best, an analyst who follows the automotive plastics market, says GM's move and DaimlerChrysler's continuing interest do not necessarily signal an industry-wide trend. Despite some forays into all-plastic IP technology, he says Ford - among others - remains cool to the concept, favoring IPs that use light metal reinforcements instead.