Maybe it began in the early 1990s, when plastics blow molders came up with multilayer fuel tanks that contained the fumes that earlier, single-layer tanks could not.
Perhaps it was before that, when the plastics guys held demonstrations that proved their tanks were surprisingly durable. Or when the Big Three got serious about corrosion resistance. Or maybe the demise of the metal fuel tank began as long as two decades ago, when the federal mandate to remove lead from gasoline also forced automakers to stop using the traditional lead-coated steel for their tanks.
One thing is for sure: Whenever the rout of metal fuel tanks started, it's now almost complete. Thermoplastic tanks have grabbed nearly half of the North American market and appear to be on their way to at least three-quarters of the business within the next several years. They're already at that level in Europe, and even the conservative Japanese automakers are beginning to agree with the appeal of plastic.
Among the Big Three, plastic tanks have seized all of Chrysler Corp.'s business and about 40 percent of new General Motors Corp. vehicles. They have created a program-by-program battle with steel-tank forces inside Ford Motor Co.
``We're pretty much moving toward plastic on all our new designs,'' said Phil Yaccarino, fuels systems manager at the GM chassis center. ``The trend over the last 10 years, industrywide, will continue.''
Said Frank Fodale, supervisor of minivan-platform fuel systems for Chrysler: ``We're glad to be 100 percent plastic already, because that gives us a leadership position in this technology, and now the rest of the industry is mid-stream in switching from steel to plastic.''
Some quarters of the steel industry already are waving big white flags.
``I don't think there's anything active in the steel industry that's going to stop the momentum plastic has gained,'' said Steve Jones, automotive applications engineer in Bethlehem Steel Corp.'s Southfield, Mich., office. ``Within our company, I know there's nothing going on to maintain our share of the market or increase it. And I know that's not good for a steel guy to say.''
The flight to plastic here is dramatic. In 1996, steel tanks had 63 percent of North American automotive volume, said Jane Warner, president of the North American arm of Kautex Werke Reinold Hagen AG of Bonn, Germany. The plastic-tank giant was acquired by Textron Automotive Co., a unit of Textron Inc., early last year. By 2002, Kautex's projections show, plastic will account for 74 percent of the North American tank market.
Brussels-based rival Solvay SA believes it may take until 2004 for plastic to get three-fourths of the North American market, while the third major player in North America, Walbro Corp. of Cass City, Mich., projects reaching the 75 percent threshold in 2005.
However, Ford's fuel-tank planning analyst, Tom Shivnani, believes while plastic's share of the tank business will continue to rise over the next two to five years, ``it won't be by a whole lot.'' Ford and the rest of the industry ``still have a major investment in steel, and we have to look at what's best overall.''
Whatever happens from here, executives of Kautex and Solvay each assert that their company is the current global-market leader, but they decline to provide statistics.
In North America, Solvay claims a market-leading 29 percent share; Kautex has 23 percent; Ford's Visteon Automotive Systems, 21 percent; and Walbro, 18 percent. Plastic Omnium SA, a French company, has a smaller but growing market share.
Because of higher gasoline prices and their smaller cars, European carmakers long have had a greater need for plastic tanks. They reduce weight and can be shaped to fit into tight spaces. In the United States, early placements included a low-volume Pontiac station wagon and a Dodge truck, said Dan Hittler, Walbro's chief administrative officer.
Big Three acceptance of the tanks took off several years ago after blow molders developed multilayer tanks of high density polyethylene that prevented fumes from escaping, meeting toughening emissions standards.
``That was really the big hurdle to get over,'' said GM's Yaccarino. Typically, an internal layer of ethylene vinyl alcohol is the key to the tanks' impermeability.
The plastics forces also convinced the Big Three of their tanks' durability with a series of punishing impact tests in which plastic tanks outperformed metal, said Francois van der Wielen, engineering director for Solvay Automotive Inc. in Troy, Mich. Early last year, Solvay opened an $80 million plastic-tank plant in Adrian, Mich.
Beyond structural integrity and impermeability, the reasons for plastic tanks' fast rise in market share have been their weight advantage over steel, much greater design flexibility and better corrosion resistance.
Plastic tanks weigh 20-30 percent less than comparable steel tanks. ``On a midsized car, that can be 5-7 pounds of weight savings,'' noted Michael Shope, Walbro's chief financial officer.
Output is headed for Chrysler and GM new-vehicle programs. While HDPE is more expensive pound for pound than steel, the two types of tanks end up costing about the same on a fully expensed basis, in part because dies for steel tank stampings are much more expensive than molds for plastic tanks, said Chrysler's Fodale.
The flexibility of plastic for tank-design purposes gives it another huge advantage. ``All-wheel-drive designs, for example, require different configurations than you can get with a steel tank,'' said GM's Yaccarino.
For the new version of a GM rear-wheel-drive model, Solvay is providing ``a tank that's almost shaped like a butterfly,'' to fit around the drive shaft, said Solvay's van der Wielen.
``You couldn't do that with steel: If anything, you'd have to have two tanks with a lot of lines in between them.'' And with Chrysler, Solvay is ``able to maximize the tank envelope by matching our CAD software with theirs,'' said David Westgate, Solvay Automotive's CEO.
GM is quickly shifting toward plastic for new-vehicle programs in North America, suppliers say. Ford is ``moving aggressively to plastic,'' said a source at the company, but is faced with ``the ongoing issue'' of competition between its Visteon parts-making unit, which manufactures plastic tanks in Milan, Tenn., and Ford Automotive Operations, which still makes steel tanks at the Rouge complex in Dearborn, Mich. Ford's Shivnani said about half the company's tanks are now plastic, but the automaker decides on each model overhaul or new program.
``If what we want to do is just a slight change from the existing steel tank, we're likely to concentrate on improving the steel tank for that new model,'' Shivnani said. Meanwhile, a Visteon spokesman said that the parts-making unit is ``actively bidding'' for new plastic-tank business from an automaker other than Ford.
Bethlehem's Jones said all Ford F-150 pickups, Econoline vans and Explorer sport-utilities use metal tanks, but Ford will switch the Explorer to a plastic tank for the 2000 model year. ``That's 400,000-500,000 tanks a year right there,'' he said.
Nissan Motor Co. Ltd. has been producing its own plastic tanks for North American models for six years using Solvay resin, van der Wielen said. That's a rare early exception to Japanese carmakers' indifference to plastic, which has only about 5 percent of their business worldwide, said Walbro's Shope.
But that attitude is changing: Honda's next-generation Civic, for all major global markets, will have a plastic tank, for example, van der Wielen said, and Walbro is supplying some Honda and Toyota programs in Europe.
Plastic's dominance over steel is becoming so thorough that the real battle lines now are among plastic suppliers themselves. Kautex's Warner believes that global manufacturing capabilities — which each of the top three plastic-tank manufacturers possesses — have become indispensable.
And as with every other system in today's vehicles, automakers are looking for fuel-system suppliers to add value, so the ability to integrate tanks into a complete modular system is proving to be essential, according to Solvay's Westgate.
Besides the tank itself, such systems typically must include the fuel pump and sender, filler neck, evaporative-emissions canister and ``any plumbing in the rear of the vehicle,'' GM's Yaccarino said. ``That's a minimum package.''
Warner said refueling-vapor-recovery components are a key issue in current design-integration efforts, and so are fuel-line connections.
``That's where most of the vapor escapes, rather than from the tank itself, but it's difficult to preassemble something of the great length of fuel lines,'' she said. ``We're looking for ways to work on that with customers right in their own plants.''
Some technological issues still dog plastic tanks, such as how the seepage of fuel into inner layers fouls the recyclability of tanks, according to Chrysler's Fodale.
And van der Wielen said that California is considering tough new regulations that would allow zero evaporation from fuel tanks, compared with a paltry amount now, and also would significantly extend the required lifetime of each tank.
Those may be just the chinks in plastics' armor that steel producers have been seeking. Moreover, some in the steel industry maintain that plastics' configurability advantage may become moot as engineers of higher-mileage vehicles ``won't have to go to such intricate shapes to find little pockets to put gasoline,'' said Darryl Martin, director of automotive applications for the American Iron & Steel Institute in Southfield.
Jones said there's a limit, anyway, on how many twists and turns can be designed into plastic tanks because if radiuses are too tight, layers of the tank begin to separate.
For the past several years, metal-tank producers have relied on the appeal of a raw material of zinc-and-nickel coated steel, covered by aluminum-rich paint and a dry-film lubricant to help in the tank-forming process. Martin said that once again, after years of watching market share leave them, steel producers are marshalling their forces for ``a big push ... to cut back into the inroads that plastics have made.'' He declines to specify what some steel companies might have in the works.
But it had better be good.