DaimlerChrysler AG is solidly behind steel as its material of choice, but nothing is carved in stone, the auto maker’s purchasing chief warns.

“We don’t exclude anything,” says Thomas W. Sidlik, management board member responsible for global procurement and supply. “There isn’t anything – purchasing-wise or engineering-wise – we’ve crossed off our list.”

DC has gained significant experience with composites and aluminum, Sidlik tells Ward’s in an interview.

“There are about six different types of composites on the (Dodge) Viper,” he notes. “The (Plymouth) Prowler was our experiment in aluminum, to see the advantages and disadvantages of that. From the technical community and the purchasing community, we have a pretty good knowledge base of the pros and cons of all the different materials.”

However, expect steel – despite its continuing upward price trajectory – to remain a mainstay at DC, especially in the wake of recent advances in the development of specialty steels.

“Clearly, our goal is to provide the highest-quality vehicle and the safest vehicle possible,” Sidlik says. “And that gets into very sophisticated types of steels, for instance, in addition to composites and aluminum.”

Hot-rolled steel is trading for about $630 per ton, down from 2004’s all-time high of $756. Consultant Roland Berger had forecast a return, this year and next, to prices in the range of $500 to $550 – figures that still were “historically high.”

But developments such as a recent 19% hike in iron-ore costs for European steel supplier ThyssenKrupp AG suggest “the soft landing may be delayed,” says Roland Berger partner Erkut Uludag.

Meanwhile, aluminum prices peaked this month at $1.25 per lb., a 20-year high. This suggests the lightweight metal that has gained favor with such brands as Jaguar and Audi likely won’t see a major boost any time soon.

“Aluminum is still too expensive,” says Paul Lacy, technical research manager with Global Insight in Detroit.

For many high-volume components, there is no better alternative than steel, Lacy adds.

Consider fuel tanks.

New evaporative emissions regulations have sucked the life out of the polyethelene fuel tank market, he says. For this application, steel is the preferred material.

Expect DC to make consistent use of the increasing variety of steels, Sidlik says. High-strength and hot-stamped steels are featured on the ’07 Dodge Caliber small car, which recently received Washington’s highest rating for frontal crashworthiness.

In tests conducted by the National Highway Traffic Safety Admin., the all-new Caliber recorded 5-star results for driver and passenger protection.

“DaimlerChrysler, typically, (prefers) steel, whether it’s a Mercedes or a Chrysler vehicle or a Jeep vehicle,” Sidlik says. “We’re talking about dozens of different types of steel in a vehicle for each individual application. Steel is still very flexible and very adaptable and very sophisticated. It’s not the steel of olden days.”

Meanwhile, Sidlik is confident DC’s purchasing power will be insulated from the proliferation of niche vehicles, a trend that could threaten strategies such as volume bundling.

“In the United States, the days of selling a million Plymouth Furys and Chevrolet Impalas and Ford Galaxies are long since past,” he says. “So the way to differentiate yourself is the niche product – smaller volumes of unique products that appeal to smaller groups of customers. But then you say, ‘How do I afford that?’

“One of the ways is a lot of common processes, a lot of common parts that don’t matter to the customer,” Sidlik says. “The customer doesn’t care about the alternator as long as it charges the battery. The successful company will not only be the one that has great styling and great design but also very creative engineering and purchasing groups that can work to keep cost down and quality high.”