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SpaceX installs full set of car-sized grid fins on second Super Heavy booster
SpaceX appears to have installed a full set of car-sized grid fins on Starship’s second flightworthy Super Heavy booster, leaving the massive rocket just a few steps away from completion.
Measuring ~69m (~225 ft) tall and 9m (~30 ft) wide, Super Heavy Booster 5 (B5) – like B4 before it – will be one of two of the largest rocket boosters ever built once completed. In broad strokes, Super Heavy B4 and B5 are the same. Aside from near-identical dimensions, both have been built to hold up to 29 Raptor engines while Starbase has already begun receiving parts of the first 33-engine Super Heavy. That means that Booster 4 and 5 – while both potentially capable of flight – are also pathfinders for an upgraded version of Super Heavy with similar dimensions but the potential to produce more than 40% more thrust once Raptor 2 production takes over.
While more similar than not, there are significant differences between SpaceX’s first and second flightworthy Super Heavy boosters.
The biggest visible differences are tweaks SpaceX has made to the Super Heavy assembly process. Booster 4 was assembled out of mostly naked steel rings and only had thousands of feet of external plumbing, wiring, raceways, and hardware installed after it was stacked to its full height. That may partially be because CEO Elon Musk had ordered SpaceX to complete the first full-height Starship stack by early August, requiring the build team to prioritize speed above all else.
Regardless, SpaceX appears to be outfitting Super Heavy Booster 5’s exterior before and during the process of stacking the booster to its final height. Most sections of 3-4 steel rings have had partial plumbing and raceways preinstalled, meaning that Booster 5 will be far closer to test readiness than Booster 4 once stacking is complete. Booster 4, on the other hand, required at least several more weeks of outfitting after SpaceX briefly rolled the rocket to the orbital launch pad for a full-stack photo-op and fit check.


On October 12th, after rapidly stacking Super Heavy B5’s upper methane tank to completion, SpaceX began installing the booster’s four car-sized grid fins. Fixed in place and assembled out of welded steel unlike the Falcon family’s deployable, cast titanium fins, Super Heavy grid fins are several times larger and heavier but still serve the same purpose of stabilizing boosters during atmospheric reentry, descent, and landing. Like Booster 4, SpaceX has also installed all four Booster 5 grid fins before stacking the Super Heavy to its full 69-meter height.
Based on B4, that final stack could happen just a few days from now, though there are signs that it might take B5 a fair bit longer. Notably, whereas Booster 4’s aft liquid oxygen (LOx) tank was already fully stacked by the start of grid fin installation, Booster 5’s LOx section is still waiting on its thrust dome. That thrust section was most recently spotted inside a production tent on October 11th – far more thoroughly outfitted than Booster 4’s aft but awaiting installation nonetheless.
That slight difference in timing pales in comparison to a massive tube that may or may not have been installed inside Super Heavy B5 late last month and that definitely wasn’t installed in B4. Without official information, it’s hard to know for sure, but the general community consensus is that this new tube (possibly one of two installed inside Booster 5’s LOx tank) is some kind of header tank or sump meant to collect propellant for Super Heavy’s boostback and/or landing burn.
If SpaceX really is adding header tanks to Super Heavy, it would drastically increase the complexity of booster plumbing, potentially explaining why Super Heavy B5’s thrust section installation is taking longer than B4. Only time (and hopefully a tweet or two from Musk) will tell.
News
Tesla Semi program Director teases major improvements
Tesla Semi Program Director Dan Priestly teased the major improvements to the all-electric Class 8 truck on Thursday night, following the company’s decision to overhaul the design earlier this year.
Priestley said he drove the Semi on Thursday, and the improvements appear to be welcomed by one of the minds behind the project. “Our customers are going to love it,” he concluded.
Just drove the redesigned Semi. Our customers are going to love it. https://t.co/KZ88sf1CDL
— Dan Priestley (@danWpriestley) December 19, 2025
The small detail does not seem like much, but it is coming from someone who has been involved in the development of the truck from A to Z. Priestley has been involved in the Semi program since November 2015 and has slowly worked his way through the ranks, and currently stands as the Director of the program.
Tesla Semi undergoes major redesign as dedicated factory preps for deliveries
Tesla made some major changes to the Semi design as it announced at the 2025 Annual Shareholder Meeting that it changed the look and design to welcome improvements in efficiency.
Initially, Tesla adopted the blade-like light bar for the Semi, similar to the one that is present on the Model Y Premium and the Cybertruck.
Additionally, there are some slight aesthetic changes to help with efficiency, including a redesigned bumper with improved aero channels, a smaller wraparound windshield, and a smoother roofline for better aero performance.
All of these changes came as the company’s Semi Factory, which is located on Gigafactory Nevada’s property, was finishing up construction in preparation for initial production phases, as Tesla is planning to ramp up manufacturing next year. CEO Elon Musk has said the Semi has attracted “ridiculous demand.”
The Semi has already gathered many large companies that have signed up to buy units, including Frito-Lay and PepsiCo., which have been helping Tesla test the vehicle in a pilot program to test range, efficiency, and other important metrics that will be a major selling point.
Tesla will be the Semi’s first user, though, and the truck will help solve some of the company’s logistics needs in the coming years.
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Tesla dominates in the UK with Model Y and Model 3 leading the way
Tesla is dominating in the United Kingdom so far through 2025, and with about two weeks left in the year, the Model Y and Model 3 are leading the way.
The Model Y and Model 3 are the two best-selling electric vehicles in the United Kingdom, which is comprised of England, Scotland, Wales, and Northern Ireland, and it’s not particularly close.
According to data gathered by EU-EVs, the Model Y is sitting at 18,890 units for the year, while the Model 3 is slightly behind with 16,361 sales for the year so far.
The next best-selling EV is the Audi Q4 e-tron at 10,287 units, lagging significantly behind but ahead of other models like the BMW i4 and the Audi Q6 e-tron.
GOOD NEWS 🇬🇧 Tesla is absolutely crushing the UK electric vehicle market in 2025 💥
The numbers are in, and the dominance is clear. With an impressive amount of 42,270 vehicles delivered year-to-date, the brand now commands a solid 9.6% market share of the total auto market 🆒… pic.twitter.com/dkiGX9kzd0
— Ming (@tslaming) December 18, 2025
The Model Y has tasted significant success in the global market, but it has dominated in large markets like Europe and the United States.
For years, it’s been a car that has fit the bill of exactly what consumers need: a perfect combination of luxury, space, and sustainability.
Both vehicles are going to see decreases in sales compared to 2024; the Model Y was the best-selling car last year, but it sold 32,610 units in the UK. Meanwhile, the Model 3 had reached 17,272 units, which will keep it right on par with last year.
Tesla sold 50,090 units in the market last year, and it’s about 8,000 units shy of last year’s pace. It also had a stronger market share last year with 13.2 percent of the sales in the market. With two weeks left in 2025, Tesla has a 9.6 percent market share, leading Volkswagen with 8 percent.
The company likely felt some impact from CEO Elon Musk’s involvement with the Trump administration and, more specifically, his role with DOGE. However, it is worth mentioning that some months saw stronger consumer demand than others. For example, sales were up over 20 percent in February. A 14 percent increase followed this in June.
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Tesla Insurance officially expands to new U.S. state
Tesla’s in-house Insurance program first launched back in late 2019, offering a new way to insure the vehicles that was potentially less expensive and could alleviate a lot of the issues people had with claims, as the company could assess and repair the damage itself.
Tesla Insurance has officially expanded to a new U.S. state, its thirteenth since its launch in 2019.
Tesla has confirmed that its in-house Insurance program has officially made its way to Florida, just two months after the company filed to update its Private Passenger Auto program in the state. It had tried to offer its insurance program to drivers in the state back in 2022, but its launch did not happen.
Instead, Tesla refiled the paperwork back in mid-October, which essentially was the move toward initiating the offering this month.
BREAKING: Tesla Insurance has just officially launched in Florida.
This is the first new state to receive @Tesla Insurance in more than 3 years. In total, Tesla insurance is now available in 13 U.S. states (map in thread below of all the states).
Tesla Insurance in Florida uses… pic.twitter.com/bDwh1IV6gD
— Sawyer Merritt (@SawyerMerritt) December 17, 2025
Tesla’s in-house Insurance program first launched back in late 2019, offering a new way to insure the vehicles that was potentially less expensive and could alleviate a lot of the issues people had with claims, as the company could assess and repair the damage itself.
It has expanded to new states since 2019, but Florida presents a particularly interesting challenge for Tesla, as the company’s entry into the state is particularly noteworthy given its unique insurance landscape, characterized by high premiums due to frequent natural disasters, dense traffic, and a no-fault system.
Annual average premiums for Florida drivers hover around $4,000 per year, well above the national average. Tesla’s insurance program could disrupt this, especially for EV enthusiasts. The state’s growing EV adoption, fueled by incentives and infrastructure development, aligns perfectly with Tesla’s ecosystem.
Moreover, there are more ways to have cars repaired, and features like comprehensive coverage for battery damage and roadside assistance tailored to EVs address those common painpoints that owners have.
However, there are some challenges that still remain. Florida’s susceptibility to hurricanes raises questions about how Tesla will handle claims during disasters.
Looking ahead, Tesla’s expansion of its insurance program signals the company’s ambition to continue vertically integrating its services, including coverage of its vehicles. Reducing dependency on third-party insurers only makes things simpler for the company’s automotive division, as well as for its customers.