Costing the Ultralite in Volume Production: Can Advanced Composite Bodies-in-White Be Affordable?

The paper investigates whether advanced composite bodies-in-white (BIW) can be affordable for mass production, using the GM Ultralite as a case study. It employs Technical Cost Modeling to compare a composite monocoque with a steel unibody across manufacturing, operation, and post-use phases. The analysis finds that while material costs for carbon fiber are high, they can be offset by significantly lower tooling and equipment costs, especially when using 'soft' composite tooling and rapid-curing technologies. The study concludes that composite BIWs can be cost-competitive with steel at carbon-fiber prices around $11/kg ($5/lb) with modest mass reductions, and are already more competitive in total lifecycle costs at production volumes below 75,000 units per year.

• Composite bodies-in-white (BIW) can achieve manufacturing cost parity with steel unibodies if carbon-fiber prices drop to approximately $11/kg ($5/lb), assuming a modest 15% mass reduction from the GM Ultralite base case.
• At production volumes below 75,000 units per year, the carbon-fiber BIW is more competitive in total lifecycle cost than the steel unibody, even without mass optimization and at a carbon-fiber price of $8/lb.
• The high cost of carbon-fiber materials can be offset by substantial savings in capital investment, specifically in tooling and equipment, compared to the requirements for steel production.
• Among the modeled tooling options, 'soft' composite tooling combined with electron-beam curing is the most cost-effective for high-volume production due to reduced equipment and labor costs resulting from rapid cycle times.
• The manufacturing cost of composite BIWs is primarily driven by material costs, making it highly sensitive to the price of carbon fiber but relatively insensitive to labor intensity.
• Increasing the production volume of carbon-fiber vehicles could trigger a positive feedback loop that lowers material costs; a 10% US market share for optimized ultralight cars could bring carbon-fiber prices down to $5/lb.
• The GM Ultralite's original BIW mass of 190.5 kg is considered unnecessarily heavy; industry experts suggest a carbon BIW could reduce standard steel-unibody mass by up to 67%.
• In ultralight vehicles, the primary motivation for further mass reduction shifts from fuel economy to reducing the cost, mass, and complexity of the driveline and the amount of expensive reinforcing fibers.

APA

Mascarin, A. E., Dieffenbach, J. R., Brylawski, M. M., Cramer, D. R., & Lovins, A. B. (n.d.). Costing the Ultralite in Volume Production: Can Advanced Composite Bodies-in-White Be Affordable? RMI. https://rmi.org/app/uploads/2017/05/RMI_Document_Repository_Public-Reprts_T95-35_CostTheUltralite.pdf

Chicago

Mascarin, Anthony E., Jeffrey R. Dieffenbach, Michael M. Brylawski, David R. Cramer, and Amory B. Lovins. Costing the Ultralite in Volume Production: Can Advanced Composite Bodies-in-White Be Affordable? RMI, n.d. https://rmi.org/app/uploads/2017/05/RMI_Document_Repository_Public-Reprts_T95-35_CostTheUltralite.pdf.

Wikipedia

{{cite report |last1=Mascarin |first1=Anthony E. |last2=Dieffenbach |first2=Jeffrey R. |last3=Brylawski |first3=Michael M. |last4=Cramer |first4=David R. |last5=Lovins |first5=Amory B. |title=Costing the Ultralite in Volume Production: Can Advanced Composite Bodies-in-White Be Affordable? |publisher=RMI |url=https://rmi.org/app/uploads/2017/05/RMI_Document_Repository_Public-Reprts_T95-35_CostTheUltralite.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{mascarinndcosting, author = {Mascarin, Anthony E. and Dieffenbach, Jeffrey R. and Brylawski, Michael M. and Cramer, David R. and Lovins, Amory B.}, title = {{Costing the Ultralite in Volume Production: Can Advanced Composite Bodies-in-White Be Affordable?}}, institution = {RMI}, url = {https://rmi.org/app/uploads/2017/05/RMI_Document_Repository_Public-Reprts_T95-35_CostTheUltralite.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }