Tesla Model S
How does the Tesla Model S Traction Control system work?
I was pulling out of the parking lot at work the other day and happened to experience some wheel spin as I drove over a patch of sand near a construction site. One wheel spun with limited grip while the other wheel pushed me through the slippery patch. The wheel modulation happened automatically and trouble free which led me to think – How does the Model S traction control work?
Before I dive into it all, one caveat: I’m an electrical/software engineer and not a mechanical engineer. I can change a tire, I used to change my own oil many years ago, but otherwise I let a trusted shop (usually a dealer) do all of the work. The information below is based on my own research and opinions.
Open Differential
I had a very basic knowledge of how the AC induction motor drives the wheels on my Model S. I thought it was just a direct current motor with a positive and negative terminal that spun one way or the other depending on polarity which in turn spun the wheels. This kind of thinking comes from my days dealing with radio control hobby kits coming out of Radio Shack. I hadn’t thought about how that may translate into driving of two wheels, nor how it would handle situations where traction is limited due to sand and ice.
It turns out, the shaft of the Model S electric motor inserts into an open differential gear box that then drives the two wheels. This gearing allows the outside drive wheel to rotate faster than the inner drive wheel during turns. Without this gearing either the inside wheel will rotate too fast or the outside wheel will drag. Any imbalance may lead to poor handling, damage to your tires and introduce a lot of stress to the drivetrain. HowStuffWorks has great animated images showing how it operates in action.
Tesla describes the gearing as follows (for the Roadster):
“The motor is directly coupled to a single speed gearbox, above the rear axle. The simplicity of a single gear ratio reduces weight and eliminates the need for complicated shifting and clutch work. The elegant motor does not need a complicated reverse gear – the motor simply spins in the opposite direction.”
The downside of the open differential approach is that torque is evenly applied to both wheels. The traction control system limits the maximum amount of torque that can be applied to each wheel without making it slip.
Turning traction control off essentially allows the motor to not back down even when one of the tires is spinning. This can often result in a lot of tire spinning and will not necessarily remove you from being stuck. In fact you may end up digging a deeper hole than the one you’re already in.
Limited Slip
Traditionally a limited slip differential allows for torque to be applied independently of each wheel. This involves complicated gearing which involves more components, adds additional weight and overall may not be as reliable on a Model S that produces such astronomical torque. For that reason Tesla chose to utilize a much simpler and sturdier open differential. But they needed to solve the slip problem.
Tesla solved the problem on the Model S by selectively applying rear brakes in order to transfer torque to the wheel that grips. These commands are fed into the electronic stability control system which is capable of braking the rear wheels independently as a way to improve the handling of the car under various conditions.
Tesla describes both traction and stability control as follows:
“Model S Traction Control is designed to ensure maximum contact between the road and the tires. Whether you are accelerating off the line, zooming along the winding roads of the Rockies or find yourself in a Gulf Coast rainstorm, Traction Control prevents loss of traction and maintains control. Stability Control reacts in moments of under-steer or over-steer by reducing torque and applying the brakes to individual wheels for enhanced control when cornering.”
Summary
Tesla Motors is about disrupting the norm and re-thinking how things should be done. If you start from scratch and question every design decision, every part, every ounce of weight, every approach and leverage the best minds on the planet, what kind of car will you end up with? The Model S is Tesla’s current answer and certainly not their final answer.
Tesla’s traction control and emulated limited slip functionality is another case of Tesla replacing complex and inefficient hardware with something lighter, simpler and more state of the art – augmenting functionality through software and algorithmic science utilizing today’s advanced computing power.
The next time you slam that “go” pedal and take off like a space ship, think about all the technology that’s helping you launch into the future.
Elon Musk
Tesla confirmed HW3 can’t do Unsupervised FSD but there’s more to the story
Tesla confirmed HW3 vehicles cannot run unsupervised FSD, replacing its free upgrade promise with a discounted trade-in.
Tesla has officially confirmed that early vehicles with its Autopilot Hardware 3 (HW3) will not be capable of unsupervised Full Self-Driving, while extending a path forward for legacy owners through a discounted trade-in program. The announcement came by way of Elon Musk in today’s Tesla Q1 2026 earnings call.
🚨 Our LIVE updates on the Tesla Earnings Call will take place here in a thread 🧵
Follow along below: pic.twitter.com/hzJeBitzJU
— TESLARATI (@Teslarati) April 22, 2026
The history here matters. HW3 launched in April 2019, and Tesla sold Full Self-Driving packages to owners on the understanding that the hardware was sufficient for full autonomy. Some owners paid between $8,000 and $15,000 for FSD during that period. For years, as FSD’s AI models grew more demanding, HW3 vehicles fell progressively further behind, eventually landing on FSD v12.6 in January 2025 while AI4 vehicles moved to v13 and then v14. When Musk acknowledged in January 2025 that HW3 simply could not reach unsupervised operation, and alluded to a difficult hardware retrofit.
The near-term offering is more concrete. Tesla’s head of Autopilot Ashok Elluswamy confirmed on today’s call that a V14-lite will be coming to HW3 vehicles in late June, bringing all the V14 features currently running on AI4 hardware. That is a meaningful software update for owners who have been frozen at v12.6 for over a year, and it represents genuine effort to keep older hardware relevant. Unsupervised FSD for vehicles is now targeted for Q4 2026 at the earliest, with Musk describing it as a gradual, geography-limited rollout.
For HW3 owners, the over-the-air V14-lite update is welcomed, and the discounted trade-in path at least acknowledges an old obligation. What happens next with the trade-in pricing will define how this chapter ultimately gets written. If Tesla prices the hardware path fairly, acknowledges what early adopters are owed, and delivers V14-lite on the June timeline it committed to today, it has a real opportunity to convert one of the longest-running sore subjects among early adopters into a loyalty story.
Tesla announced its Spring 2026 software update, and it’s the most feature-dense seasonal release the company has put out. The update covers twelve named changes spanning FSD, voice AI, safety lighting, dashcam storage, and pet display customization, among other things.
The centerpiece for owners with AI4 hardware is a redesigned Self-Driving app. The new interface lets owners subscribe to Full Self-Driving with a single tap and view ongoing FSD usage stats directly in the vehicle.
Grok gets its biggest in-car upgrade yet. The update adds a “Hey Grok” hands-free wake word along with location-based reminders, so a driver can now say “remind me to pick up groceries when I get home” without touching the screen. Grok first arrived in vehicles in July 2025, but each update has pushed it closer to genuine daily utility. Musk framed the broader vision clearly at Davos in January, saying Tesla is “really moving into a future that is based on autonomy.”
On safety, the update introduces enhanced blind spot warning lights that integrate directly with the cabin’s ambient lighting, building on the blind spot door warning that arrived in update 2026.8.
Dog Mode has been renamed Pet Mode and now lets owners choose a dog, cat, or hedgehog icon and add their pet’s name to the display.
Dashcam retention now extends up to 24 hours, up from the previous one-hour rolling loop, with a permanent save option for any clip. Weather maps now show rain and snow with better color differentiation and include the past hour of precipitation data along the route.
Tesla has now established a clear rhythm of two major OTA pushes per year. As with last year’s Spring update, that cycle started taking shape in 2025 with adaptive headlights and trunk customization. The 2025 Holiday Update then added Grok to the vehicle for the first time. This Spring follows that structure: the Holiday update introduces new architecture, and the Spring update broadens it across the fleet.
Two notable features still did not make it. IFTTT automations, which launched in China earlier this year, were held back from this North American release for unknown reasons, and Apple CarPlay remains absent, reportedly still delayed by iOS 26 and Apple Maps compatibility issues.
Below is the full list of feature updates released by Tesla.
— Tesla (@Tesla) April 13, 2026
Elon Musk
Tesla launches 200mph Model S “Gold” Signature in invite-only purchase
Tesla’s final 350-unit Signature Edition closes the book on two cars that changed everything.
Tesla has announced a super limited Signature Edition run of 250 Model S Plaid and 100 Model X Plaid units as an invite only purchase in a bid to give its original flagship vehicles a proper send-off.
When the Model S first launched in 2012, the first 1,000 units sold were “Signature” editions that required a $40,000 deposit and cost nearly $100,000 each. Those early buyers were Tesla’s first real believers. This new Signature Edition deliberately echoes that moment, bookending a 14-year run with numbered collector hardware.
Both models are finished in an exclusive Garnet Red paint not available on any current Tesla production vehicle, with gold Tesla T badges up front, a gold Plaid badge and Signature badge at the rear, and a white Alcantara interior featuring gold Plaid seat badges, gold piping, Signature-marked door sills, and a numbered dash plate. The Model S adds carbon ceramic brakes with gold calipers. Every unit ships with Tesla’s Luxe Package, bundling Full Self-Driving (Supervised), four years of Premium Service, free lifetime Supercharging, and a Signature Edition key fob. Both are priced at $159,420, a roughly $35,000 premium over standard Plaid inventory.
The discontinuation is part of a broader strategic shift. At Tesla’s Q4 2025 earnings call, Musk described the decision as “slightly sad” but necessary, saying: “It’s time to basically bring the Model S and X programs to an end with an honorable discharge, because we’re really moving into a future that is based on autonomy.”
The Fremont factory floor that built these cars is being converted to manufacture Optimus humanoid robots, with a target of one million units annually.
SpaceX just got pulled into the biggest Weapons Program in U.S. history
Tesla pulls back the curtain on Cybercab mass production
