We get our first view at hardware 4.0 for the Model Y
Greentheonly/Twitter
In a recent series of fascinating tweets, @greentheonly provided an unprecedented look into the internals of Tesla's new Model Y Hardware 4 or HW4. With his expertise and knowledge, Green shared detailed observations on the HW4's physical structure, board components, and the viability of retrofitting older models, giving the Tesla community much to ponder.
Breaking Down the HW4's Structure
Green's exploration of the HW4's complexities commenced with him acknowledging an "anonymous donor" for providing a chance to look inside Model Y's HW4. The serial numbers and other identifiers were blacked out. Green stated it was done to protect the donor after previous experiences, "Tesla is vengeful like this and went after the guy that did hw2.0 teardown by trying to deny warranty on unrelated repairs. Does not help that this new computer now has a (borderline illegal) 'warranty void if removed' sticker."
Delving into HW4's Core: Circuitry and Components
First up on the dissection table was the computer's physical form factor. According to Green, the HW4's form factor mirrors those of the S/X models, putting to bed any speculation around a potential retrofit to HW3 cars.
Moving deeper into the HW4, Green revealed that the board layout is similar to the HW4 on the Model S. However, as Green termed it, specific components, including the GPU and superior sound hardware, are now missing or depopulated. The use of cheaper non-Error-Correcting Code ram (ECC RAM) also seems to be a cost-cutting measure implemented by Tesla in this version of HW4 on the infotainment system side. Interestingly, this version of HW4 features two additional but depopulated display connectors, hinting at possible a possible second display in the vehicle.
Other distinguishing attributes of HW4 include a reoriented BroadR-Reach ethernet and the addition of a third, depopulated ethernet. Moreover, Green pointed out that the gateway chip has changed, too, with a different model from another vendor now in use. This chip, which was only seen in Chinese-made boards previously, seems to be a standard feature in all Model Y HW4 boards now.
Retrofitting HW3 to HW4: More Than Meets the Eye
The idea of retrofitting HW3 cars with HW4 stirred up quite a debate. According to Green, the concept may sound enticing, but it's not as straightforward as it seems. Modifying the vehicle to accommodate the new coolant pipe locations would be necessary for a retrofit, likely making this option more costly than simply manufacturing a new board in the old form factor.
Uncovering the Hidden Changes
Apart from the apparent changes, Green shared insights into some of the subtle modifications made by Tesla. For instance, the Texas-manufactured Model Ys feature a plastic "firewall" requiring a change in mounting methods for the new HW4. Despite the internal components remaining the same, the different mounting technique necessitates a unique part number for the computer.
The missing camera connectors were for additional cameras, such as a front bumper camera. However, as Green says, the absence of a connector doesn't mean that Tesla won't add them in the future. In fact, if Tesla had no intentions of adding such features, they wouldn't be available on the board at all, instead of just being unpopulated.
Implications for Current and Prospective Tesla Owners
For existing and future Tesla owners, these findings offer a clearer understanding of what to expect from the HW4-equipped Model Ys. Notably, questions still linger about additional cameras and if and when newer models will receive them. The Cybertruck prototype already has a front bumper camera, so it may only be a matter of time.
While it seems that retrofitting HW3 to HW4 may not be feasible due to the cost and complexity involved, Green isn't entirely ruling out the possibility. He believes a different version could theoretically be created for retrofits, although it's unlikely.
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Tesla signaled its intention to launch its first Robotaxi network in Austin, Texas, with company-owned and operated vehicles, back in January. This network will be Tesla’s first foray into truly autonomous vehicles - ones that aren’t being directly supervised by a driver. Later in February, Tesla’s executive team confirmed that the plans were on track for the launch of the Austin network both on X and during several interviews that they participated in.
At the end of February, we also found out that Tesla has applied for a Supervised Robotaxi license in California, where the network will also launch, but with safety drivers in place.
This is an ambitious plan, but FSD has really come a long way in the past year. FSD V12 was a massive step forward from V11, and V13 has made the experience smoother and safer than ever before. FSD V14 is expected to be another big step up with auto-regressive transformers and audio input.
Still on Track
Now, Elon has tripled down on the fact that Tesla will be launching their first autonomous robotaxi network in Austin - just two months away at this point. It seems that Tesla is fully set to launch their first fully unsupervised self-driving vehicles that will carry paying passengers in June.
Additional Cities
The best part is that Elon also confirmed that they’re targeting robotaxi networks launching in many cities within the United States by the end of this year. However, remember that this will be a Tesla-run network at first - Tesla owners won’t be able to add their vehicles to the Robotaxi fleet right away.
Adding Customer Vehicles
It will take some time before Tesla meets their strict internal safety requirements before it lets customers add their own vehicles to the network. Tesla’s executive team mentioned that they intend to let owners add their own vehicles to the fleet sometime in 2026. This happens to be the same time frame that Tesla plans to launch the Robotaxi across the United States, Mexico, and Canada — something that could only be done with customer-owned cars.
That final step will be bold—and it may come with complications, especially given that autonomous vehicle approval spans municipal, state or provincial, and even federal levels. There are plenty of regulatory hurdles ahead, but this is undoubtedly shaping up to be one of the most exciting times for Tesla.
Launch Event
With the Robotaxi network launching and Unsupervised FSD just around the corner, there’s a lot to get excited about. Tesla is expected to host a launch event at Gigafactory Texas in Austin to mark the debut of its first Robotaxi network. The company previously hinted that referral code users could receive invites—offering a rare chance to score an early ride in a Robotaxi outside the Hollywood studio lot.
Tesla’s engineering mule vehicles—used to test autonomy for future platforms—have resurfaced after an extended absence. The last time we saw them was back in July, when Tesla was gearing up for its initial We, Robot event. Since then, sightings have been scarce.
These vehicles typically signal that Tesla is testing new camera placements or validating FSD ground-truth data. This time, however, they appear to be outfitted exclusively with the updated camera hardware seen on the Cybercab.
New Sightings
The mules have now been spotted in Boston, Massachusetts, and Concord, New Hampshire—their first known appearances this far east. This suggests Tesla is actively collecting data to evaluate and optimize FSD performance in new regions. Thanks to Reddit user Ready_Medium_6693 for catching the one in Concord.
Elon Musk recently mentioned that Tesla plans to expand Robotaxi networks beyond the initial Texas and California launches. So while these sightings aren’t entirely unexpected, the speed of their arrival is. It suggests Tesla is confident in its ability to train FSD for local traffic rules and driving behaviors to the point it no longer needs a driver.
Bumper Cameras
The vehicle that’s been spotted in Boston is the usual Tesla engineering Model 3… except with one unique twist. It includes a front bumper camera. Shout out to @Dylan02939106 for catching the bumper camera in these photos.
The Refreshed Model 3 Mule with a Bumper Camera!
@Dylan02939106 on X
We previously released an opinion piece regarding whether the front bumper camera would be required for Unsupervised FSD. In our eyes, Tesla will require a bumper camera for Unsupervised FSD - if only to improve direct visibility in the bumper area of the vehicle. This is key for low-speed maneuvering in crowded areas like parking lots and garages, as well as for key features like Actually Smart Summon.
It isn’t surprising that Tesla is continuing to evaluate vehicles with a bumper camera - the Cybertruck, Cybercab, and Refreshed Model Y all have them now - and the rest of the lineup, including the flagship Model S and X, as well as the refreshed Model 3 - were supposed to eventually receive them as well.
With the Model S and Model X set for refreshes this year—and the front bumper camera on this Model 3 looking well-integrated rather than a temporary setup—it seems likely that front bumper cameras will soon become standard across Tesla’s entire lineup.
The Robotaxi Mule in Boston
@Dylan02939106 on X
In fact, Tesla’s newest iteration of the FSD computer has a slot for the Bumper Camera on all AI4/HW4 vehicles, so a future retrofit could even be possible.
These are some pretty exciting times - we may see Robotaxi networks actually deploy in time for Tesla’s lofty goal of “sometime in 2026” for cities throughout North America. Once many American cities begin to accept their deployment, it will be easier to seek homologation in Mexico and Canada, enabling deployment throughout the continent.
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