The performance gap between HW3 and AI4: reports from March 2026

The numbers don't lie

TESMAG (teslaacessories.com) published a technical analysis in March 2026 evaluating the difference in performance between Tesla Hardware 3 and AI4, based on fleet-level reports on disengagements (moments when FSD hands control back to the driver because the system can't proceed).

The reported figures:

• AI4 vehicles: approximately 450 miles between critical disengagements
• HW3 vehicles: approximately 120 miles between critical disengagements

The ratio is roughly 450 : 120, meaning HW3 performs approximately 3.75 times worse on this specific safety-related metric.

A note on the source

These numbers come from reporting by TESMAG, an independent tech publication that follows Tesla fleet data and FSD releases. They aren't numbers Tesla has officially published with its own press release. For litigation it's advisable to use these numbers as supporting evidence (article 160 of the Dutch Code of Civil Procedure), with the primary evidence resting on Tesla's own party statements (the patent, the Elluswamy tweet, Musk's earnings quote).

The reason these numbers still carry weight is that they're consistent with what Tesla's own VP Ashok Elluswamy declared publicly in August 2024 and what Tesla's own CEO Elon Musk declared in January 2025: HW3 runs a 'smaller model' and can't deliver the full functionality. The TESMAG report puts a concrete number to what Tesla has already admitted.

Why Tesla has to use the workaround

According to TESMAG's analysis, with quotes from technical developers:

"To run v13 on HW3 silicon, Tesla engineers had to 'prune' the neural network and 'quantize' the weights from 16-bit to 8-bit."

In plain terms: to run FSD v13 on the HW3 chip, Tesla engineers had to shrink the neural network and reduce its precision by half.

This is the same approach Tesla describes in its own patent application US20260017503A1 (see evidence item 7). It's not an experimental optimisation. It's the only way Tesla can squeeze a usable amount of functionality onto HW3. And as the patent itself acknowledges, this approach can render the system 'inoperable' at critical moments.

Dutch weather makes it worse

The TESMAG report contained a specific note on regional variation. Initial data suggested HW3 vehicles lag even more behind AI4 in complex weather:

"Initial data suggests HW3 vehicles may be slightly more 'hesitant' in complex Dutch weather conditions compared to the fluid performance of AI4."

For Dutch owners this matters specifically: rain, fog, wet road reflections, and autumn leaves are exactly the conditions in which an autonomous driver gets tested. If HW3 performs even worse there than AI4, the safety gap in Dutch practice may be larger than the average number suggests.

HW3 can't even meet the original 2019 promise

In 2019 Tesla literally promised:

"Every Tesla is equipped with the hardware needed in the future to make the car fully self-driving under nearly all circumstances, at a level of safety we believe is twice as safe as the average human driver."

In 2026 Tesla publishes on its Dutch FSD page (see evidence item 10) a claim that the system is '7x safer' than a human driver, without any hardware distinction. If that figure of 7x applies to AI4 vehicles, and HW3 vehicles perform roughly 3.75 times worse than AI4, then HW3 comes in at approximately 7 / 3.75 = 1.9 times safer. That's less than the 2x that Tesla originally promised in 2019.

In other words: Tesla isn't just failing to meet the upgraded 2026 claim on HW3. Tesla is failing to meet even its own original 2019 promise. That's a quantifiable, numerically supported defect in the delivered product.