Study shows mega casting can be cheaper to repair than traditional structures

A new study suggests that vehicles incorporating aluminium mega cast technology can deliver substantial repair cost savings compared to traditional multi-piece steel constructions, challenging early industry concerns about repairability.

The two-year study was conducted at the headquarters of Thatcham Research in the UK, where Tesla Model Y vehicles, which feature a single piece, aluminium rear floor section, were subjected to a series of physical crash tests, followed by damage assessments and repair technique tests.

The Tesla Model Y’s one-piece, mega cast rear chassis section, consolidates around 70 individual components into a single aluminium casting, to reduce manufacturing time, cost and environmental impact.

Thatcham Research claims this technique, which several other vehicle manufacturers are planning to introduce, can also reduce repair costs in both partial and full replacement scenarios when compared to conventional steel, multi-piece vehicle structures.

Tesla Model Y with full mega casting on display

“Our research demonstrates that mega cast technology when properly implemented with comprehensive repair guidelines, can deliver significant benefits for insurers, consumers and the environment,” said Richard Billyeald, chief research & operations officer at Thatcham Research.

“The Tesla Model Y’s repair costs were consistently lower than comparable vehicles with traditional construction while maintaining structural integrity and repairability standards, which reduces the chances of a vehicle being written off in common accidents, improving its lifecycle CO2 benefits.”

The investigation, designed to simulate damage from real-world claims collected from UK insurers and conducted in cooperation with Allianz Centre for Technology (AZT) in Germany, subjected vehicles to controlled impact tests at varying severities to assess both damageability and repairability characteristics.

Comparative analysis revealed that the Model Y’s mega cast construction delivered consistent cost advantages across multiple scenarios. Partial replacements cost £2,167 less than the Model 3’s traditional multi-part steel rear sub-assembly construction, while full replacements saved £519.

Similar patterns emerged when comparing against other manufacturers’ vehicles, with the Model Y demonstrating lower repair costs than other models, including the Mercedes-Benz EQE, Hyundai Ioiniq 5, and several internal combustion engine vehicles.

“The key insight from our testing is that vehicle manufacturers must integrate repairability into the design of a mega cast component,” explained Darren Bright, principal engineer, automotive repair at Thatcham Research.

“In Tesla’s case, the inclusion of replaceable cast rear rail assemblies at just £31 each provides a cost-effective solution for minor impacts, while the relatively low cost of full replacement mitigates concerns about more severe damage scenarios.

“Without this provision of reasonably priced partial and full replacement parts and the associated repair procedures, our findings would have been very different.”

Industry implications
The mega cast chassis has important implications for sustainability. In practical terms, lower repair costs mean that damage which might have resulted in a total loss on a traditionally constructed vehicle is now more likely to be economically repairable. Fewer write-offs translate to more vehicles remaining in service after collisions, preserving the energy and materials already invested in their manufacture and delaying the environmental cost of early replacement.

With manufacturers including Toyota, Volkswagen, Volvo, and Hyundai announcing mega cast implementation plans, Thatcham Research says its research provides essential benchmarking data. Toyota’s planned implementation will replace 177 components across front and rear castings, while Volvo’s single-floor pan cast will consolidate 100 components.

“Tesla has established important precedents for mega cast repairability, but our research highlights areas requiring industry-wide standardisation,” noted Billyeald. “As this technology proliferates, establishing comprehensive repair protocols, non-destructive test procedures, and technician training programmes will be essential for maintaining vehicle safety, insurance and lifecycle sustainability.”

Thatcham Research says it is developing comprehensive documentation to enhance the industry’s existing understanding of mega cast implications and will continue to monitor and evaluate new mega cast implementations as they emerge.