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Tesla ‘Roadrunner’ cell leak hints that Battery Day will be more insane than expected
Tesla’s Battery Day has been hyped so much that the event will have to include something truly amazing to live up to its expectations. In the lead up to the highly-anticipated event, a leaked image featuring what is supposedly a cell from Tesla’s “Roadrunner” line has emerged. And if the leak proves legitimate, it would appear that Battery Day will not only meet expectations — it will be even more insane than expected.
The leaked image, which was initially published in a report on Electrek, featured a massive battery cell that was supposedly a product of the Roadrunner line. The publication noted that the image was sent through an anonymous source and confirmed by another independent source. From the get-go, it is evident that the cell is massive, closer in size to a supercapacitor than a traditional battery cell. Initial observations by battery enthusiasts online also point to some radical improvements that such a cell design would bring.
While Electrek’s sources have mentioned that the Roadrunner cell will feature roughly double the diameter of the 2170 cells that the electric car maker currently uses in the Model 3 and Model Y, Tesla enthusiast @_BRCooper, who is familiar with battery tech, has observed that one of the leaked images had the number “054” printed on its side. If this number represents the cell’s diameter, it would point to Tesla’s Roadrunner cells adopting a 54×98 form factor, which has 10x the volume of a 2170 cell.
As noted by Jordan Giesige of The Limiting Factor channel on YouTube, adopting a 54×98 form factor for its next-generation cells has numerous implications for the entire battery manufacturing process and the performance of Tesla’s vehicles as a whole. With the larger cells, Tesla could produce battery packs that have an order of magnitude fewer cells than before. This would result in the company only using 1/10 the number of rolls, cans, electrolyte fills, and welds compared to its current operations. Such a strategy opens the doors to massive cost reductions that could help bring down the prices of electric cars to a notable degree.
But regardless of its actual size, the design of the Roadrunner cell appears to be optimized and designed for a cell-to-pack drop-in setup. Interestingly enough, the leaked image of the Roadrunner cell seems to have a tabless electrode design, which Elon Musk has dubbed is “way more important than it sounds” last year. Provided that the Roadrunner cells are indeed inspired by Tesla’s tabless electrode patent, the new form factor could pave the way to more performance and further reductions in production costs.
What’s even more notable is that these improvements become possible with just the Roadrunner cell’s new form factor and design. Giesige, for his part, has noted that with the Roadrunner cell’s design and potential 54×98 form factor alone, Tesla may be able to close in on 300 wh/kg before making any significant changes to its battery chemistry. Elon Musk actually mentioned a 30-40% improvement from 250 wh/kg back in 2018, which translates to an improvement to 325-350 wh/kg. Musk’s prediction was considered fantastical by critics then, but as Battery Day approaches and leaks start to emerge about the event, it is starting to look more and more likely that 325-350 wh/kg is feasible.
Watch a feature on the Roadrunner battery cell leak in the video below.
Tesla has finally and officially confirmed that Actually Smart Summon, commonly known as ASS, will make its way to the Cybertruck two and a half years after first deliveries.
The feature, which is part of the Full Self-Driving suite, allows owners of any Tesla to literally summon their vehicle to their location in a parking lot. It is limited by range and speed, especially as there is nobody in the vehicle, but is a great feature to have for rainstorms, busy parking lots, or for injured passengers (I recently used it so I could give my Fiancèe a hand leaving a sports injury doctor after she pulled her calf).
Tesla Summon has been a lifesaver for picking up my Fiancèe as she pulled her calf during a 10-mile race in Philadelphia this past weekend!
It went from one of her least favorite features of the Tesla to one of the most useful:pic.twitter.com/CPs6lTSPA8
— TESLARATI (@Teslarati) May 6, 2026
Summon has been available on every Tesla that is currently available, but the Cybertruck has not had the feature in the two and a half years that customers have been taking deliveries.
There were a few things that Tesla had to work out with Full Self-Driving features, Summon in particular, with the Cybertruck.
Initially, its Steer-by-Wire system handles low-speed maneuvers differently than a typical mechanical steering connection available in the S3XY lineup. This required some additional time of development to allow Tesla to retrain and validate the AI models specifically for the feature within Cybertruck.
Additionally, the overall size and weight of Cybertruck impacted expected dynamics, has an impact on braking distances, and even obstacle avoidance in tighter lots. Tesla prioritized safety over launching the feature ahead of having the utmost confidence in it.
However, the wait is finally over, at least it seems that way. Tesla said that Cybertruck will receive ASS through a Software Update “shortly,” but did not give an explicit date. Tesla has said that Summon is coming in the past, only for it to be delayed yet again.
Summon for Cybertruck rolling out shortly https://t.co/rGli2iHbtL
— Tesla (@Tesla) June 10, 2026
We anticipate that Summon will roll out within the Cybertruck in less than a week, but there are still some reservations about that timing because, ultimately, nobody knows what Tesla will do outside of Tesla. The Spring Update for many came well late, at least a month past the initial rollout wave.
The rollout of Summon to Cybertruck is a great milestone for Tesla, even if it has come later than most would really like to admit. Now that Cybertrucks will be summoned across parking lots, it will be awesome to see reactions to the massive pickup with no driver sitting in the driver’s seat.
Tesla has secured regulatory approval for its Full Self-Driving (Supervised) system in Denmark, marking a significant step in the technology’s expansion across Europe.
Announced on June 9, the approval positions Denmark as the fourth European country to greenlight FSD Supervised, following the Netherlands, Lithuania, and Estonia.
Rollout to Danish vehicle owners is expected to begin soon, the company said.
The Danish Road Traffic Authority granted provisional approval after reviewing the original type approval issued by the Dutch vehicle authority (RDW) on April 10, 2026.
FSD Supervised now approved in Denmark 🇩🇰
Rollout will begin soon pic.twitter.com/Xpxwcme10k
— Tesla Europe, Middle East & Africa (@teslaeurope) June 9, 2026
This national recognition approach allows individual countries to bypass slower EU-wide harmonization processes, accelerating deployment. Lithuania activated the system on May 20, with Estonia following on May 29, demonstrating a rapid domino effect across the region.
FSD Supervised enables advanced driver assistance capabilities, including automatic steering, acceleration, braking, lane changes, and navigation through complex urban and rural environments. The system is designed for supervised use, as its name states, meaning drivers must remain attentive and ready to intervene at all times.
It adapts to diverse conditions, such as rain, night driving, and varied road types common in Denmark, but it is important to note that the tech is not fully autonomous.
Following a launch in Europe just a few months ago, with its first approval coming in the Netherlands, Tesla is just now highlighting the successful start.
Early data from the Netherlands highlights strong safety performance. Between April 10 and June 5, vehicles using FSD Supervised recorded 3.5 times fewer collisions than manual driving overall, with zero crashes reported on highways across more than 16.6 million kilometers driven.
These results underscore the potential of the technology to enhance road safety when properly supervised.
Tesla’s European push builds on its global footprint, now reaching 12 countries with FSD Supervised availability. The software receives continuous over-the-air updates, improving performance based on real-world data from millions of miles.
In Denmark, owners with compatible hardware—particularly newer vehicles equipped with Hardware 4 (HW4)—are anticipated to gain access first, though exact timelines and eligibility details will be confirmed during rollout.
This approval reflects growing regulatory confidence in supervised autonomy across Europe. As more nations recognize the Dutch certification, Tesla continues to demonstrate how its AI-driven approach can navigate real-world driving scenarios effectively. Denmark’s addition strengthens Tesla’s position in the region, paving the way for broader adoption on a continent that his been surprisingly slow to adopt the technology.
With FSD Supervised now approved in four European markets in just two months, the technology is steadily advancing toward wider availability. Tesla aims to refine the system further through ongoing data collection and software iterations, supporting its vision for safer and more efficient transportation.
Tesla has apparently revised the policy it previously had listed for Full Self-Driving transfers on the newest All-Wheel-Drive Cybertruck that the company had sold for a steal price of just $59,000 earlier this year.
After initially stating that customers who bought the pickup would be able to transfer FSD purchases, Tesla recently changed the language in those terms and conditions to reflect that this would no longer be the case.
Tesla launches new Cybertruck trim with more features than ever for a low price
The adjustment in terminology has caused a handful of orderers to cancel their reservations due to the loss of FSD transfer:
Just cancelled my 59k CT order today. My screenshot from that day of order (feb 20th) clearly shows that it would be eligible.
Terms were retroactively modified. Our 2020 Y and 2023 S are just fine for now. pic.twitter.com/D9PFnId1B4
— Ryan Scanlan 👥 (@Xenius) June 8, 2026
Tesla said orders for the new Cybertruck AWD must be placed by March 31, 2026, to qualify for the FSD transfer. The language in the document from earlier this year explicitly states that they “may qualify” for the transfer program, but the date of March 31 is explicitly mentioned.
Additionally, Tesla Delivery Advisors reached out to some orderers of the AWD Cybertruck, who were told there was “an update to the eligibility of the Full Self-Driving (Supervised) transfer.” Tesla stated they could:
- proceed without the transfer,
- upgrade to a Premium or Cyberbeast trim and request an FSD Transfer
- cancel the order and be refunded the $250 order fee.
Tesla turning around and changing these terms will undoubtedly result in a handful of cancellations on the part of those who have placed an order for this truck. They could pay $99 per month for an FSD subscription, which is now the only option available, but having purchased the suite outright on another vehicle and being told the transfer policy would be upheld, only to have it cancelled, is a tough pill to swallow.
These moves were also made by Tesla just before deliveries were set to begin on the Cybertruck AWD configuration. Reservation holders have started receiving VINs for their trucks, and Tesla is preparing to hand over the first units.
It’s a disappointing move from Tesla that will undoubtedly make some of its fans who have bought the truck frustrated.
Tesla confirms it’s releasing a long-awaited Cybertruck feature
Tesla Full Self-Driving is taking over Europe: fourth country gets FSD approval
