Thatcham Research: Tesla’s mega cast technology can reduce repair costs compared to traditional structures

Key findings:

• A two-year Thatcham Research study finds Tesla’s “Mega Casting” can be cheaper to repair than traditional steel structures.
• The research, supported by real-world insurer data and AZT (Allianz Centre for Technology) Germany, shows cost advantages when manufacturers integrate repairability into mega cast design.
• Tesla’s repair guidelines now set a new industry benchmark, though the study identifies opportunities for broader standardisation.

The two-year investigation, triggered by concerns from the insurance industry about the potential cost of repairing large single-piece aluminium castings after rear-end collisions, was conducted using Tesla Model Y vehicles. These vehicles feature a single-piece aluminium rear structure that replaces around 70 individual components to reduce manufacturing complexity and environmental impact.

The study found that properly implemented mega cast designs—supported by strong engineering and comprehensive repair procedures—can result in lower repair costs, without compromising structural integrity or safety.

“Our research demonstrates that mega cast technology, when supported by detailed repair guidelines, can deliver major benefits for insurers, consumers, and the environment,” said Richard Billyeald, Chief Research & Operations Officer at Thatcham Research. “Tesla’s Model Y consistently showed lower repair costs than comparable vehicles with conventional structures, helping reduce vehicle write-offs and improving lifecycle CO₂ performance.”

Real-World Data and Measurable Savings

The study, conducted with input from UK insurers and the Allianz Centre for Technology (AZT) in Germany, used controlled crash testing and real-world claim data to assess both damage and repairability.

Comparative analysis revealed consistent cost advantages for the Tesla Model Y:

• Partial replacements were on average £2,167 cheaper than those for the Model 3’s traditional steel subframe.
• Full replacements cost £519 less than equivalent conventional repairs.

These cost benefits were also observed when comparing the Model Y against other EVs and combustion vehicles, including the Mercedes EQE and Hyundai IONIQ 5.

“The key insight is that repairability must be part of the mega cast design process,” explained Darren Bright, Principal Engineer, Automotive Repair at Thatcham Research. “Tesla’s use of replaceable rear rail assemblies costing just £31 each makes minor repairs highly cost-effective, while keeping full replacement costs competitive.”

Without affordable spare parts and clear repair procedures, Bright noted, these advantages would not be achievable.

Industry Implications: Repairability and Sustainability

The research carries major implications for the automotive industry’s shift toward sustainable manufacturing and lifecycle management. Lower repair costs mean fewer total losses—reducing waste and preserving the embedded energy and materials in each vehicle.

With major manufacturers like Toyota, Volkswagen, Volvo, and Hyundai set to adopt mega cast technology, Thatcham Research’s findings establish critical benchmarks. Toyota’s upcoming platforms, for instance, will consolidate 177 components across front and rear castings, while Volvo plans to merge 100 parts into a single cast floor section.

“Tesla has set important precedents for mega cast repairability,” said Billyeald. “But as more OEMs adopt this technology, the industry must standardise repair protocols, develop non-destructive test methods, and expand technician training to ensure safety and sustainability.”

Thatcham Research will use the findings to support the development of industry standards, training programmes, and repair guidelines, preparing repair networks for the widespread adoption of large-scale castings.

Deep Dive: Tesla Model Y Testing

• Low-severity impacts (15 km/h): The Model Y’s mega cast structure sustained no structural damage, allowing full vehicle repair without replacing the casting.
• Medium-severity impacts (25 km/h): Full mega cast replacement was required due to cracking and misalignment—but the £716 component cost kept total repair expenses competitive with traditional methods.

However, the research also highlighted practical challenges, such as the need for Tesla-approved facilities for aluminium welding and the logistical complexity of handling large, irregular castings.

Thatcham Research also emphasised the need for improved non-destructive testing (NDT) procedures to detect hidden damage and ensure safe, reliable repairs.

Outlook

The full report—available to Thatcham Research members—includes detailed technical data, cost comparisons, and best-practice recommendations for insurers, OEMs, and repair professionals preparing for the mega cast era.

As manufacturers increasingly move toward large-scale aluminium casting, Thatcham Research’s findings underline a clear message:

When designed with repairability in mind, mega cast technology can reduce costs, cut emissions, and extend vehicle lifecycles.