Tampa Steel Conference: Steel grades reallocate as aluminum holds ground in auto design

The discussion moved beyond simple material substitution and centered on how production levels, powertrain trends, regulatory changes and consumer cost pressures are shaping material decisions.

From 337 to 85 grams

Ducker Carlisle’s Abraham outlined the regulatory path that drove much of the industry’s recent material strategy.

In 2022, the average light vehicle sold in the US emitted roughly 337 grams of CO2 per mile. Under the Biden administration, the Environmental Protection Agency set a fleetwide target that would have lowered emissions to 85 grams per mile by 2032. That trajectory required roughly 10% annual reductions through the end of the decade.

Abraham described that move from 337 to 85 grams as a “monumental task,” stating there was “no way to get to 85 grams per mile without a significant share of BEVs.”

The EPA’s multipollutant emissions rule operated alongside fuel economy requirements administered by the National Highway Traffic Safety Administration (NHTSA).

However, the 2025 passage of Trump’s One, Big, Beautiful Bill removed NHTSA’s ability to impose civil penalties for OEMs failing to meet EPA targets. The Trump administration said post-2026 targets could be frozen or abandoned.

As regulatory pressure shifts, the focus of efficiency changes. Rather than engineering against penalty thresholds, automakers weigh consumer cost, performance and range.

That said, the industry’s initial response to the earlier target left lasting changes in powertrain design, transmission strategies and material selection.

Potential approaches

Automakers responded to emissions pressure through three primary pathways.

First, they pursued internal combustion engine improvements that offered incremental efficiency gains. Second, they expanded electrification. Third, they reduced vehicle mass and improved aerodynamics.

Within the ICE category, manufacturers downsized engines, added turbochargers and superchargers, and deployed increasingly complex transmissions. The spread of 8-, 9-, 10-speed automatic gearboxes allowed engines to operate closer to optimal efficiency bands. Stop-start systems became more common.

These changes did not require full electrification, yet they produced measurable fuel economy gains. ICE improvements could account for somewhere between 15%-20% of the CO2 emissions reduction targets.

Electrification offers the largest theoretical emissions reduction of anywhere from 50%-70% under the modelled reduction framework. But cost, charging infrastructure and consumer demand mitigate its pace.

Although lightweighting accounts for the smallest modelled share of emissions reduction potential at 6%-15%, it is the only pathway among the three showing an upward, near-term trend in importance through 2032.

That shift helps explain why the industry’s material discussion has centered on aluminum, particularly extrusions, as well as increasingly complex grades of steel. Lightweighting remains relevant across both ICE and electric platforms and offers manufacturers a way to improve efficiency regardless of powertrain mix.

Material mix shifts in steel and aluminum

If lightweighting is gaining relative importance as a near-term efficiency level, the material mix shows how manufacturers are responding in practice.

Abraham noted the composition of the average North American vehicle continues to evolve and is actually set to increase by 2027 compared to 2022.

According to the material mix analysis of compositional mixes from 2022 to 2027, the average weight of North American light vehicles will rise by around 2.6% throughout that period, according to Ducker Carlisle.

Aluminum

Rolled aluminum used in the average North American vehicle increases only slightly to 62 kilograms, while cast aluminum — the largest share of aluminum content by weight — remains at 137 kilograms, even as total vehicle weight rises 2.6%. Forged aluminum also holds steady at 5 kilograms through 2027.

Extruded aluminum rises sharply by 31%, representing the largest percentage increase among aluminum categories. That growth aligns with ongoing discussion around structural extrusions and new joining techniques, even as overall cast aluminum weight per vehicle does not expand.

While gigacasting continues to generate industry attention, the data show total cast aluminum mass remains unchanged over the forecast period.

Steel

Steel shifts significantly, but largely within its own grades.

Advanced high-strength steel use increases by a little more than 19% over the period to 259 kilograms through 2027. At the same time, conventional steel sheet declines 4% to 413 kilograms, and “other” steel declines by 9% to 243 kilograms.

Abraham explained one pound of advanced high-strength steel can replace about 1.2 to 1.3 pounds of mild steel, which accounts for this internal transition.

Overall, steel and iron together account for about 53% of vehicle weight by 2027, compared with roughly 67% in 2006. However, the near-term picture from 2022 to 2027 looks different.

Total vehicle weight increases and the conventional sheet and “other” steel content drops over the 2022 to 2027 period. When steel and iron are grouped together, total ferrous mass per vehicle declines by around two kilograms over the five-year period.

When iron is excluded and only steel categories are aggregated, total steel mass Is actually one kilogram higher.

In percentage terms, steel’s share declines modestly because overall weight increases. In absolute kilograms, however, the shift from 2022 to 2027 represents more of a reallocation of steel grades, rather than a contraction in total steel content.

Material swaps

The discussion moved away from broad material trends and into how decisions get made at the program level.

Abraham cautioned against viewing the shift between steel and aluminum as a direct swap. “You can’t consider it a one-to-one replacement,” he said.

Instead, material selection depends on applications.

Structural components such as door beams and side-impact structures remain tied to press-hardened steels because crash performance sets hard constraints. At the same time, closures and selected structural applications can move back and forth between materials depending on cost targets and supplier positioning.

Suppliers may hold roughly 30-60 days of inventory, Abraham said, but that short coverage window should not be confused with the much longer vehicle development cycle. He also noted vehicle programs are locked in year before production.

A typical start-of-production cycle can take roughly 48 months to plan, which limits abrupt changes. That timing, combined with supply chain considerations and inventory strategies, tempers dramatic swings in either direction.

Production levels stabilize

North American vehicle production no longer points to rapid expansion.

Forecasts presented during the session show gradual recovery toward the mid-16-million-unit range later in the decade, following an extending period between 15 million to 16 million units. As volumes stabilize, automakers concentrate on cost control and program discipline rather than aggressive expansion.

For context, prior to the 2020 Covid-19 pandemic, 2019 North American light vehicle output totaled around 16.2 million units, which is only anticipated to be surpassed by the year 2029.

Even so, as Abraham put it, “I don’t think that we’ll see an 18-million-unit production in the US again [or in Mexico] in the next decade.”

ICE and hybrids retain share

Electrification continues, but not at the pace once projected.

Battery electric vehicle share has grown since 2019. However, the removal of certain federal incentives and consumer affordability concerns have slowed expansion.

Although Ducker Carlisle expects battery electric vehicle platforms to account for roughly one-quarter of North American vehicle production by the end of the five-year period. Internal combustion engine vehicles and hybrids that retain ICE components will still account for about three-quarters of the market. BEV growth is not expected to accelerate meaningfully until around 2028, implying that most of the share gains are a few years out, the firm said.