Mega cast repair savings revealed in Thatcham Research study

A new study by Thatcham Research has revealed that aluminium mega cast vehicle structures – pioneered by Tesla – can deliver substantial repair cost savings compared to traditional steel constructions, provided they are supported by robust design and repair protocols.

The two-year project, based at Thatcham Research’s Berkshire headquarters and supported by real-world claims data from UK insurers and Allianz Centre for Technology (AZT) in Germany, focused on the Tesla Model Y. The vehicle features a single-piece, aluminium rear chassis – consolidating around 70 components into one casting.

Contrary to early concerns from the insurance industry, Thatcham Research found that the mega cast rear structure delivered lower repair costs in both partial and full replacement scenarios. Partial repairs were £2,167 cheaper than those on the Model 3’s conventional steel assembly, with full replacements saving £519. These cost advantages were also observed in comparisons with other vehicle brands, including Mercedes, Hyundai, and various ICE models.

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

Key to Tesla’s success was the inclusion of low-cost, replaceable rear rail assemblies at just £31 each, allowing cost-effective repairs following minor impacts. However, Thatcham Research also noted that aluminium welding repairs to mega cast structures can only be carried out at Tesla-approved facilities, raising questions around network readiness and repair logistics.

Low-severity crash tests at 15km/h showed no structural damage to the mega cast, while medium-severity tests at 25km/h required full replacement due to crack propagation and alignment issues. Yet even in these cases, the Model Y’s repair costs remained competitive.

The research also highlighted operational challenges for repairers. The size and shape of mega castings may limit repair capabilities at smaller facilities, and the need for non-destructive testing (NDT) procedures was emphasised to detect hidden structural damage effectively.

As other manufacturers – including Toyota, Volvo, Volkswagen and Hyundai – move to adopt mega casting, the study provides essential guidance. Thatcham Research is now developing technical documentation and training to support industry adaptation, ensuring repairability remains central to the wider rollout of this technology.

For further information visit Thatcham Research