General Motors has had quite enough of the punishment Honda, Toyota and others have been doling out for years. Throughout most of the 1990s, GM’s mid-size car market share bombed — from nearly half of that critical segment’s volume to less than a third. Since 1988, GM has squandered some four million sales to competitors. Something had to be done to keep the world’s " />
Chevrolet’s Malibu rides on a 2,700 mm wheelbase version of the Epsilon platform. A long wheelbase version (Malibu Maxx) stretches to 2,852 mm by using different front and rear sections mated to a common center floor panel. All Epsilon cars share a front strut suspension and four-link rear with identical mounting points and wheel travel. Suspension tuning takes place through bushings, spring rates and shock calibration.
To find out how Epsilon can succeed in the wake of global car designs that failed, we tapped two experts on the subject. One of them, GM vehicle line executive Gene Stefanyshyn, was not only present at Epsilon’s 1997 creation, he’s also the architect of several of GM’s key global strategies.
Formulating the Epsilon solution began six years ago. Stefanyshyn notes, “The planning began in 1997 among German, Swedish and American engineers at the (Warren) Tech Center. The first step was acknowledging the Catera was not the way to do a global car design. We realized that bringing all parties to the table early was essential to success. We found that everybody’s got to be in the mood to make love.
It’s hard to gain someone’s attention when their next model change is five years out; they’ve got too many other things to worry about that are more urgent. So cadence is critically important.”
The timing plan for every Epsilon-based product was laid out at the very beginning of the project. Knowing exactly when each of the vehicles would roll-out globally was a major enabler for a smooth transition from product to product.
“Opel was first in line,” Stefanyshyn says. “So the Epsilon task force relocated to GM’s International Product Development Center in Russelsheim, Germany, but not before we had debated key elements such as basic dimensions, safety targets and suspension layouts. Opel started filling in the details with our guys in attendance. When the timing was right, Saab engineers moved to Germany to participate in the learning and to tailor Epsilon to their specific needs.”
Somewhat later, additionalU.S. engineers relocated to Europe. Lyndon Schneider, program engineering manager for Malibu and 20 or so others were in Germany for nearly three years.
Another early but critical task was defining exactly what is meant by a global car. Some makers use that term to mean a global brand selling the same products in far flung markets. But for GM, global does not constitute what Stefanyshyn likes to call a “Coca-Cola car.” Instead, Epsilon is a common architecture capable of yielding regional products. That’s because GM’s past attempts at the Coca-Cola approach have not worked.
“Living and working in various markets are essential to identify the major differences from one locale to another,” Stefanyshyn stresses. “Taxation, government regulations and customer tastes change when you cross borders and continents. So the GM plan is leveraging one very good global architecture and allowing various regions to tailor the design to suit their particular markets. The goal is achieving a high degree of technical competence rather than selling exactly the same car worldwide.”
|Opel’s Vectra was the first Epsilon-based car in production, but the rollout plan for every iteration was decided before work on Vectra ever began. The car was engineered in GM’s International Product Development Center in Russelsheim, Germany. Engineers from all divisions selling Epsilon sat in during development. |
|Saab’s 9-3 (top) is a departure from other Epsilon models due to Saab’s insistence on body structure and vehicle safety. It uses the same platform but everything from the floorpan up is strengthened. The Pontiac G6 concept (above) is said to carry the styling cues for the Epsilon-based Grand Am. |
Interestingly, Saturn, which would capitalize on Epsilon’s composite panel capability, is one of the eight Epsilon brands although GM has not yet officially confirmed its inclusion.
Stefanyshyn’s U.S. partner in crime, Greg Bellopatrick, is chief engineer for GM’s mid-size line of vehicles. He notes, “We believe there are varying degrees of commonality. In Epsilon, fuel tanks, rear cross members, steering knuckles, struts, lower control arms and engine cradles may differ slightly from market to market but they’re all interchangeable.” The front suspension is a strut package that always locates the same way and provides the same ride travel in every application. All of the Epsilon cars share one four-link independent rear suspension though each is tuned differently in terms of bushings, spring rates, shock absorber calibration, etc. The rear cradle can be mounted rigidly to the car or rubber isolated. But given all the features shared throughout Epsilon, it can accurately be called an architecture with a high degree of commonality.
“If you lined up all the Epsilon variations hoists to look underneath,” Bellopatrick offers, “you’d conclude they’re all the same. But because these are high volume products, the flexibility available in tooling allows us to change details as needed to tailor each product for its regional market.” Components like engine mounts, for example, are different to provide a major distinction between a Saab and a Chevrolet.
Also, the notion of pothole durability seems be very different around the globe. “Germans look at you in disbelief when you explain the need to conduct the brutal durability tests we run,” says Bellopatrick. They’re understandably reluctant to add unsprung mass to suspension components unless it’s absolutely necessary.
Since we have separate tooling and we don’t intend to ship parts across the ocean, we use the flexibility we have to tailor parts to specific market applications.”
Commonality in degrees also filters down to the supplier level. Stefanyshyn explains, “Faurecia supplies all of our seat frames. They’re stamping parts both here and in Europe. Saab and Opel need a lot of content in their seats but the Chevrolet Malibu is at a lower price point so it might have a manual versus a power lumbar adjustment. However, under the upholstery, the basic seat architecture is common.” In addition to body structures and chassis parts, there are electrical systems consider. Again, the priorities differ around the globe. Notes Stefanyshyn, “In America, we tend to pack all the computing capability in one body computer, using serial data link to communicate with remote modules. Our goal is to reduce the number of body computers used by GM from 40 or so today down to one with medium content and one with high content for the future.”
But that isn’t an optimum fit with the Opel Vectra which is sold as an affordable Chevrolet in export markets such as Brazil.
To accommodate those applications, Opel prefers to spread its computing power over multiple modules interlinked with two-way communication. That allows them to select cost-effective modules as needed, thereby avoiding the expense associated with one body computer that’s more powerful than necessary.
“Trying too hard to commonize electronic components also squanders the opportunity to take advantage of cost reductions occurring on practically a daily basis,” Stefanyshyn adds. “You’ve got to be fast on your feet in the infotainment area but that’s not possible when you commit to one electronic component to be shared by multiple car lines launching over a period of months or years.
Another matter is how electronic systems evolve. For example, electrically assisted power steering (EPS) wasn’t able to pass noise targets when the Opel Vectra was under development so passed on the technology. But Chevrolet had an extra 18 months to solve that concern, and was able to include EPS in the Malibu. In the final analysis, neither interchangeable nor common parts are the driving force behind Epsilon. Instead, the carrot is what GM calls technology transfer. “The keys,” reveals Stefanyshyn, “are speed and quality. Even though every Epsilon car requires its own validation process, by living under one umbrella we achieve higher quality answers more quickly.”
As an example, Stefanyshyn recalls how the Epsilon program assembled a safety integration team so that as Opel crashed its first Epsilon cars, Saab engineers were present to observe and learn so they were higher on the experience curve when their turn to conduct the same tests arrived. “In Europe, safety standards are geared to belted occupants,” he notes, “while in the U.S., federal standards specify unbelted occupants. So Opels comply one way and U.S. products must meet different standards."
|THE EPSILON EIGHT|
Pontiac Grand Am
|Gene Stefanyshyn intends to transform GM's mid-size segment. |