Braking is essential to the driving experience, but not all systems are created equal. A regenerative braking system (RBS) is the most significant difference people notice the first time they operate an electric vehicle.
Regen, as commonly referred to, makes it possible to drive a Tesla and never touch the brake pedal (along with some brake blending for slow speeds), not only reducing wear and tear on braking components but putting energy back into the battery. There are some estimates that regenerative braking can add 10 percent more range and extend the life of braking mechanisms by more than 50 percent.
What is Tesla's Regenerative Braking?
Unlike traditional brakes, which rely on friction to stop the wheels from turning, regenerative braking uses the vehicle's electric motor to create resistance to slow down the vehicle. In addition to slowing the vehicle down without the use of brakes, the motor running in reverse acts as a generator and captures the kinetic energy that would typically be lost as heat and converts it into electrical energy, thereby increasing your vehicle's range.
How to Activate Regen in a Tesla
In a Tesla, the regenerative braking system is activated by lifting your foot off the accelerator. The more you ease off the accelerator, the stronger the braking force and the more energy is captured.
Tesla's Power Meter (Regen bar)
Tesla's power meter, also known as the regen bar or line
Not a Tesla App
All Teslas feature a power meter either in the instrument cluster (Model S and X) or the center screen (Model 3 and Y) that displays the amount of energy being captured through regenerative braking, or the amount of energy being used by accelerating the vehicle.
The center of the line is considered neutral. Anything to the left of the center point means energy is being captured, while anything to the right means that energy is being used.
The further the line grows to the left, the greater the amount of regenerative braking is taking place, and the more it moves to the right, the greater the amount of power is being used.
The regenerative braking line is green, while the power line is black (or white when in dark mode). You may occasionally also see a gray line on the left side. This will appear if the vehicle has the 'Apply Brakes When Regenerative Braking Is Limited' feature turned on. This feature introduces a consistent braking experience when lifting your foot off the accelerator pedal when regenerative braking is limited.
You may also see the gray line appear on the left side of the power meter if the vehicle is in Autopilot. This helps the driver understand when the vehicle is using regenerative braking or physical brakes to slow down.
Without getting too deep into Physics, kinetic energy is energy in motion. Therefore, anytime a car slows down, the kinetic energy that is produced has to go somewhere. With traditional brakes, that is heat from abrasion generated from the brake pads squeezing the rotors. But this energy can be used in a different way. In the words of a Tesla engineer, "kinetic energy stored in a moving vehicle is related to the mass and speed of the vehicle by the equation E = ½mv²."
You can see this equation play out every time you drive your Tesla by looking at the vehicle's power meter.
The motor controller manages the torque of the motor. This action helps with both driving and regenerative braking. The position of the accelerator pedal tells the motor controller how much torque is needed. The motor controller then changes this into a voltage or current that produces the correct torque. The rotating force can be positive or negative. When it is negative, it means the vehicle is slowing down, and energy is returned to the battery.
Regenerative Braking Explained
Regenerative Braking Extends the Life of Your Brakes
One of the benefits of regenerative braking is that it can help to lengthen the life of your brakes. Regenerative braking slows the car reducing the work of your traditional braking system. In fact, Tesla estimates that their cars experience 50 percent less brake wear than conventional gasoline cars. Elon Musk predicted that Tesla's Semi would have brake pads that would "literally last forever" because the regenerative system would save those pieces from being used extensively.
It's estimated that regenerative braking captures up to 70 percent of the kinetic energy usually lost during braking and is put back into the battery. As described above, that energy can then extend the range between needing to charge.
Does Regenerative Braking Activate Your Brake Lights?
During regenerative braking, Tesla will still activate the brake lights when the vehicle is slowing down, even if the brakes aren't being used at all. Tesla determines whether to turn on your brake lights based on your vehicle's rate of deceleration. If you're unsure if your brake lights are on, look at your Tesla screen, the car in the display shows the brake lights lit up when the brake lights are activated.
Levels of Regenerative Braking
It's important to note that regenerative braking cannot be turned off. There are two regenerative braking modes for 2020 and older models — low and standard. Tesla recommends that you use standard to maximize your vehicle's range. At some point in 2020, that choice was taken away, presumably to use all the benefits of regenerative braking all the time. However, there were some concerns, as regenerative braking can slow down the car rapidly; therefore limiting traction, the vehicle could slide. Tesla has this warning on its website: In snowy or icy conditions, Model S may experience loss of traction during regenerative braking.
Tire Configuration
The company also notes that installing winter tires may temporarily reduce regen. But the vehicle's systems are constantly recalibrating, so the feel of the vehicle will return to what the driver is used to after a few miles or trips.
You can speed up the calibration process by selecting the type of tires your vehicle is using. To select the type of tires your vehicle is using navigate to Controls > Service > Wheel & Tire Configuration > Tires and choose the appropriate tire type.
Regenerative Braking Limited or Reduced
Regenerative braking is not available or can be limited during certain conditions. If this happens, you may see a dotted line in the vehicle's power meter. If the battery is fully charged, there is nowhere for the kinetic energy to go. Consequently, regen won't work. It also has limited usage during cold weather due to a cold battery. In these cases, you can choose to activate 'Apply Brakes When Regenerative Braking Is Limited' to provide a consistent slow down experience. Tesla stated, "Your car can now automatically apply regular brakes for consistent deceleration when regenerative braking is limited due to battery temperature or state of charge." But the company did leave this as a preference, and the option can be turned off. You can activate it under Controls > Pedals & Steering.
Stopping Modes
Regenerative braking works best at certain speeds, if you're traveling too slow, regenerative braking may be limited or not available at all.
In a Tesla, your vehicle will use regenerative braking whenever you lift your foot off the accelerator pedal. However, if you're using Tesla's 'Hold' stopping mode, which allows you to drive with a single pedal most of the time, the vehicle will automatically blend in the vehicle's brakes when traveling 4 MPH (6.5 KPH) or slower.
If you're using Tesla's 'Creep' or 'Roll' stopping modes, the vehicle will never apply the brakes when lifting your foot off the accelerate, which means the vehicle will continue to roll at slow speeds when regenerative braking is no longer effect.
A Brief History of Regenerative Braking
Tesla used regenerative braking in its first car — The Roadster, in 2008. A year later, the same mechanics of the system were implemented in Formula 1. It is called KERS, which stands for Kinetic Energy Recovery System. It provides such a horsepower boost that it was banned for a season before being regulated the following year. However, this advanced system dates back to the late 1800s.
The Sprague Electric Railway and Motor Company is the earliest known use of the technology in 1886. General Electric used regen in 1936 in its locomotives, and Oerlikon, a Swiss company utilized some components of the system in its gyrobus. The Amitron, a concept electric car created by the American Motor Car Company included regenerative braking in its designs. Toyota introduced the technology to its brand with the Prius Hybrid in 1997 and GM's EV1 had regen when the company sent the cars to the crusher.
Regenerative braking is now a staple of the electric vehicle experience, not only reducing maintenance costs but also improving the vehicle's range and letting drivers accelerate and slow down with a single pedal.
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While we haven’t even seen AI5, Tesla is already thinking about its next set of chips that will power Tesla’s future FSD computers. In a set of posts on X, Elon Musk outlined the future of Tesla’s AI hardware, stating that its “strategic importance is hard to overstate.” He also revealed that Samsung, the current manufacturer of Tesla’s AI4 chip, will produce the next-generation AI6 chip at a new, dedicated fabrication facility in Texas.
While AI4 is already used in Tesla’s Robotaxis, which are practically driving autonomously, it’s hard to imagine where the company will be with a computer that’s many more times as powerful. Things like the recent video of a Tesla stopping at a toll booth, waiting for the driver to pay, and then taking off will become commonplace, not only at booths but also in various nuanced scenarios, such as someone waving you by, or stopping for a friendly neighbor that waves you down.
Samsung’s giant new Texas fab will be dedicated to making Tesla’s next-generation AI6 chip. The strategic importance of this is hard to overstate.
Samsung currently makes AI4.
TSMC will make AI5, which just finished design, initially in Taiwan and then Arizona.
To understand the need and brilliance behind why Tesla is doing what it's doing with AI6, we need to take a look at the problem it is being engineered to eliminate. Currently, Tesla, like many others, faces a real two-language problem in its AI development.
The vast majority of its AI training is done on a supercomputer cluster, Cortex, which is built around Nvidia’s powerful H200 GPUs. However, the vehicles that run the software use Tesla’s custom-designed hardware - HW3/AI3 or HW4/AI4. This means that every time the AI model is improved - whether the vision neural nets or the ones that determine distance, or any of the many little parts that come together to build FSD as a whole - there’s a whole second step. It must be developed and validated on Nvidia’s architecture, then rebuilt and re-validated to run on Tesla’s own AI hardware.
Tesla runs AI4 chips side-by-side with the H200 GPUs in Cortex to minimize this, but that still means there is a step in between the training getting completed and the actual model being able to run on a vehicle. This slows down the feedback loop from training to deployment, even if Tesla has built a Universal Translator to help move FSD from one piece of hardware to another.
AI6 Solution: One Chip to Rule Them All
AI6 is the definitive solution to this problem. While the upcoming AI5 chip (to be made by TSMC) represents a performance leap over AI4, AI6 will be a transformative leap in architecture.
The key innovation of AI6 is the direct integration of Tesla’s Dojo Supercomputer chip architecture into the same hardware that will be in Tesla’s vehicles and Optimus. The goal is to closely integrate the training and vehicle hardware.
By having the same Dojo architecture in the data center for training and in the vehicle for inference, Tesla will have a single, unified hardware pipeline. The two-language problem vanishes, drastically simplifying Tesla’s development process and enabling a much faster pace of innovation and updates.
Manufacturing Collaboration
The plan for AI6 goes beyond just chip design. Elon’s announcement revealed that Tesla plans to build a strong manufacturing partnership with Samsung. After all, much of Tesla’s expertise is focused on the machines that build the machines.
Samsung has agreed to allow Tesla to assist in maximizing manufacturing efficiency at the new Texas fab. It’s unusual to see this kind of relationship between the fabricator and the client. Elon doubled down on this - he wants to walk the fab lines to personally accelerate the pace of progress.
Samsung agreed to allow Tesla to assist in maximizing manufacturing efficiency.
This is a critical point, as I will walk the line personally to accelerate the pace of progress. And the fab is conveniently located not far from my house 😃
Tesla isn’t just designing the chip, but helping to make sure it’s made in the most efficient and optimal way possible, all while leveraging Tesla’s experience and Samsung’s fab skills in one facility.
Fully Integrated
Tesla’s AI6 announcements come as a surprise since Tesla is still a year out from releasing AI5, but it shows that Tesla plans to integrate even more of its AI stack. From influencing the manufacturing process of the chip itself to designing a unified hardware architecture for both training and inference, Tesla is building a self-reinforcing ecosystem.
This approach will create a feedback loop that allows for rapid improvement. While AI5 will be a big step up from the current generation, AI6 is revolutionary as it becomes Tesla’s major AI platform.
At the recent X Takeover event this past weekend, two of Tesla’s most important leaders gave in-depth interviews that provided a unique view into Tesla’s path forward and how everything comes together internally.
An interview with Elon Musk laid out the grand vision for Tesla and his other companies, focusing on the ambitious “what and why.” Later, Head of Vehicle Engineering Lars Moravy provided the more grounded, engineering-focused “how,” detailing the immense work it takes to turn the vision into a reality.
What emerged from these conversations was a clearer picture of Tesla’s strategy: a relentless, long-term vision for the future of transportation, AI, robotics, and energy, supported by a world-class engineering team capable of developing the processes to turn these products into a reality.
Robotaxi & Cybercab
For years, the concept of Unsupervised FSD, as well as Robotaxis, has been the focal point of Tesla’s future. In his interview, Elon provided fresh details on the way they expect the business model to work. Tesla plans to operate a fleet where some vehicles are company-owned, while others are owned by customers. This is essentially a combination of Uber and Airbnb, taking a bit of a hybrid approach between the two different styles.
He also went on to confirm that the purpose-built, two-seater Cybercab would complement, but not replace, Tesla’s existing models. This is key, because many have thought that Tesla would end their consumer vehicle sales or drastically reduce them as they transitioned to an AI services company, and became less of a car company. Now, it seems we know that they’ll have a lasting stake in personal car ownership.
The Cybercab, which is a revolutionary vehicle without driver controls, requires an equally revolutionary process to build it. In his interview, Lars Moravy provided the answer and detailed the unboxed manufacturing process that Tesla has been developing.
The unboxed method challenges a century of established automotive assembly by breaking the vehicle down into smaller, parallel sub-assemblies, allowing more work to be done simultaneously. The goal is to drastically shorten the main assembly line, enabling vehicle sections to be built in parallel and come together at the end.
Lars also noted that Tesla has already done the initial batch of crash testing for the Cybercab prototypes, and the vehicle has passed with flying colors. This isn’t surprising for Tesla, which integrates vehicle safety right into the structure of the vehicle, building castings that transfer force away from occupants.
The Semi
While Elon’s interview focused on some of his grander ambitions like Mars colonization, Lars provided some tangible updates on two of Tesla’s most anticipated vehicles.
On the Tesla Semi, Lars confirmed that progress is well underway at the Semi factory in Reno, Nevada. After years of focusing on engineering prototypes to ensure the reliability of a commercial workhorse vehicle, Tesla is now expected to ramp up production by the end of 2025, continuing through into early 2026. The business case for the Semi is crystal clear - build a no-brainer choice for shipping and logistics companies, who need to weigh the initial buy-in and infrastructure costs against operating costs per mile.
The Semi, just like other EVs, absolutely trumps diesel trucks in cost per mile, due to lower energy costs and less maintenance. However, the somewhat hidden advantage here is that truck drivers drastically prefer to drive the Tesla Semi over other diesel trucks, citing things such as better visibility, a smoother ride, and easier driving. These are advantages that could lead to improved employee retention and easier driver recruitment.
Meanwhile, the Semi simply needs to have infrastructure installed at the starting and ending locations for major delivery companies, enabling end-to-end supply chain handover.
The Roadster
Lars also talked about Tesla’s upcoming Roadster, confirming that it’s still in development, with the team preparing for a mind-blowing demo sometime soon. Elon previously hinted at this demo during a visit to the Tesla Design Studio, where he said a mind-blowing demo would be coming by the end of the year.
The goal for Tesla is to make it the last, best driver’s car before the world begins transitioning to full autonomy. Lars also touched on one of the biggest challenges with the Roadster. There is an immense engineering challenge being taken on now - and it's the SpaceX package. This package is set to use cold-gas thrusters to push the Roadster past what is conventionally possible. In fact, just as Elon has previously mentioned, the Roaster may be able to “fly a little.”
Last, best driver’s car
Lars Moravy
You can watch the full interview below. Lar’s portion on the Roadster starts at 26:30.
Optimus: Sustainable Abundance
One of the most ambitious parts of Elon’s vision is the Optimus humanoid robot. He has stated his belief many times that the robotics business could be many times more valuable than Tesla’s entire automotive business, and if it works as planned, it definitely will be.
The current Optimus V3 design is intended for volume production, with Elon foreseeing a future market of billions of humanoid robots - not made just by Tesla, but the market as a whole. That many units could simply eliminate human poverty and usher in an age of sustainable abundance.
That grand vision is built on top of the manufacturing and automation expertise that Lars’ team is pioneering every day. With volume production of Optimus to begin next year, and real work already being done in Tesla’s factories, we may see humanoid robots making a real impact on the lifestyle and livelihood of people within the next few years.
The Unfair Advantage: Getting Sh*t Done
All of these ambitious ideas and products are enabled what what is perhaps Tesla’s true sauce - its unique internal culture of getting sh*t done. Lars’ interview provided us with a rare look inside to see just how it all comes together.
He described working with Elon as unique - the discussions are grounded in physics, and Elon trusts his teams to turn his dreams and ambitions into reality. This, in turn, creates a culture of mutual respect and high expectations.
The collaborative spirit extends to the relationship between engineering and design, which Lars described as highly unusual for the auto industry. Rather than the two teams being hostile to each other, they work together to make bold design and engineering choices, like the Cybertruck, into reality.
Underpinning all of this is what Lars himself calls Tesla’s superpower: in-house automation and manufacturing engineering teams. These teams work to design the machine that builds the machines - innovating and solving problems at a level and speed that is simply not possible when relying on external vendors.
This combination of a relentless long-term vision, alongside a first-principles engineering culture, allows Tesla to take big risks and make big plays that define its future path. While all of Tesla’s timelines are ambitious, these interviews make it clear that the ambitious vision is paired with a concrete and innovative plan for execution.
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