Tesla’s 4680 battery self-sufficiency goals face significant hurdles following reports of underperformance in European Model Y vehicles.

Tesla quietly tested the in-house batteries in select European models, leading to customer concerns.

Customers report the 4680 cells represent a downgrade compared to packs supplied by LG Energy Solution.

The 4680 cells show a reduced driving range of up to 52 kilometers.

The new format also demonstrates lower energy density than partner-supplied cells.

Charging times for an 80% charge have increased to 40-45 minutes.

Previous packs reached the same charge level in under 30 minutes.

These performance gaps challenge the 2020 promise of the 4680 format as a revolutionary advancement.

Manufacturing and optimization challenges continue to hinder the mass production of the new battery format.