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SpaceX begins testing first flightworthy Super Heavy booster
More than three months after the building-sized Starship booster’s latest return to Starbase’s orbital launch site, SpaceX has finally begun the process of testing what CEO Elon Musk says is still the first flightworthy Super Heavy.
After completing a number of pad tests in the days prior, SpaceX began filling Super Heavy Booster 4 (B4) with liquid nitrogen – supplied by the first orbital-class Starship launch – for the first time on December 17th. It’s unclear exactly what was done during the test but regardless of what transpired, the test and B4’s survival were a major, long-awaited milestone for both the Starship booster and the orbital launch site (OLS).
At this point in time, the general consensus among close followers of SpaceX’s Starship program is that the unprecedented amount of time it’s taken the company to complete Booster 4’s first test was not because of the rocket itself but rather because the orbital launch site needed to fully test it had yet to be completed. While it was SpaceX’s choice to not perform some kind of initial testing with B4 at one of the site’s two suborbital test and launch mounts, it’s clear that the company ultimately concluded that Super Heavy Booster 3’s successful July 2021 tests – including a cryogenic proof virtually identical to Booster 4’s first test – made such partial testing redundant.
Put a different way, SpaceX must already be confident enough in the quality of the first few Super Heavies rolling out of its Starbase factory to deem it unnecessary to verify the structural integrity of the first truly completed Super Heavy booster before putting the one and only orbital Starship launch site directly in the line of fire. Nonetheless, depending on how far Super Heavy Booster 4’s first cryogenic proof test went, it appears that SpaceX’s presumptions were correct.
On December 17th, SpaceX subjected Super Heavy B4 to a cryogenic proof test about twice as ambitious as B3’s, filling the booster maybe a sixth of the way with a few hundred tons of liquid nitrogen (LN2). What isn’t clear is if that test also raised the booster’s propellant tanks to flight pressures (6-8 bar or 90-115 psi). If Booster 4 did reach those pressures, the test is even more significant – partially proving that the rocket is ready for flight. On December 21st, SpaceX performed a similar series of cryogenic tests, again partially filling Booster 4 with about the same amount of liquid nitrogen but doing so two or three times in a row. Again, the Super Heavy survived the several-hour ordeal without any obvious issues. Still, a number of additional tests – some even more important – are still in front of SpaceX and Super Heavy B4.
The most obvious is simple enough: SpaceX needs to fully fill a Super Heavy booster for the first time. Depending on the storage situation, that process will likely begin by filling Booster 4 with about 2500 tons (5.5M lb) of liquid nitrogen (LN2) – about two-thirds full. If SpaceX also temporarily fills one of the orbital tank farm’s liquid oxygen (LOx) or methane (LCH4) tanks with nitrogen, it could fully load Booster 4 with around 3500 tons (7.7M lb) of nitrogen. At least according to SpaceX’s own website, that’s about the same weight as the propellant (3400t/7.5M lb) Super Heavy is designed to lift off with. If that full cryoproof goes well, SpaceX will then likely perform one or several wet dress rehearsals, ultimately filling Booster 4 with approximately 2900 tons (6.4M lb) of cryogenic oxygen and 500 tons (1.1M lb) of cryogenic methane.
Finally, SpaceX will probably kick off static fire testing, likely beginning by igniting just one or a few of Super Heavy’s many engines. Eventually, that process could culminate in the ignition of all 29 of Booster 4’s Raptors, briefly producing a bit less than 5400 tons (~11.9M lbf) of thrust – 50% more powerful than NASA’s retired Saturn V Moon rocket.
According to Elon Musk, despite a number of recent signs and reports to the contrary, SpaceX still intends to fly Booster 4 and Ship 20 on Starship’s first orbital-velocity launch attempt, so the scope and scale of testing are only likely to grow over the next several weeks.
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Tesla Model Y dominated China’s NEV sales in December 2025
As per sales data from China, the all-electric crossover finished first among the country’s best-selling EVs and plug-in hybrids.
The Tesla Model Y ranked as China’s top-selling new energy vehicle in December, leading an intensely competitive market packed with strong domestic brands.
As per sales data from China, the all-electric crossover finished first among the country’s best-selling EVs and plug-in hybrids. The Model 3 also placed within the country’s top ten vehicles.
Model Y leads China’s NEV rankings
The graphic, shared on X and sourced from Chinese auto industry data aggregator Yiche, listed the top 20 best-selling new energy vehicles in China for December. Tesla’s Model Y claimed the No. 1 position with roughly 65,874 units sold, finishing well ahead of a field dominated by domestic manufacturers such as BYD, SAIC-GM-Wuling, and Xiaomi.
The chart also showed strong performances from other high-volume models, including BYD’s Qin Plus, which sold 46,837 units during the month. Tesla’s Model 3 ranked eighth overall, with just under 28,000 units sold, placing it ahead of numerous locally produced competitors despite its rather premium price.
Tesla China’s strong December
Tesla China had a stellar December 2025. During the month, Tesla sold 97,171 vehicles wholesale in China, as per data from the China Passenger Car Association (CPCA). The result marked Tesla China’s second-highest monthly total on record, trailing only November 2022’s peak of 100,291 units.
December’s wholesale figure represented a 3.63% increase from the same month a year earlier and a 12.08% jump from November. Industry watchers have suggested that part of the surge was driven by Tesla pulling deliveries forward to allow customers to benefit from more favorable purchase tax policies before year-end.
Despite this, December’s results suggest that Tesla’s Model Y and Model 3 remain highly competitive offerings in China, which is extremely impressive considering the competition from domestic players and their still premium price.
Elon Musk
Elon Musk’s net worth is nearing $800 billion, and it’s no small part due to xAI
A newly confirmed $20 billion xAI funding round valued the business at $250 billion, adding an estimated $62 billion to Musk’s fortune.
Elon Musk moved within reach of an unprecedented $800 billion net worth after private investors sharply increased the valuation of xAI Holdings, his artificial intelligence and social media company.
A newly confirmed $20 billion funding round valued the business at $250 billion, adding an estimated $62 billion to Musk’s fortune and widening his lead as the world’s wealthiest individual.
xAI’s valuation jump
Forbes confirmed that xAI Holdings was valued at $250 billion following its $20 billion funding round. That’s more than double the $113 billion valuation Musk cited when he merged his AI startup xAI with social media platform X last year. Musk owned roughly 49% of the combined company, which Forbes estimated was worth about $122 billion after the deal closed.
xAI’s recent valuation increase pushed Musk’s total net worth to approximately $780 billion, as per Forbes’ Real-Time Billionaires List. The jump represented one of the single largest wealth gains ever recorded in a private funding round.
Interestingly enough, xAI’s funding round also boosted the AI startup’s other billionaire investors. Saudi investor Prince Alwaleed Bin Talal Alsaud held an estimated 1.6% stake in xAI worth about $4 billion, so the recent funding round boosted his net worth to $19.4 billion. Twitter co-founder Jack Dorsey and Oracle co-founder Larry Ellison each owned roughly 0.8% stakes that are now valued at about $2.1 billion, increasing their net worths to $6 billion and $241 billion, respectively.
The backbone of Musk’s net worth
Despite xAI’s rapid rise, Musk’s net worth is still primarily anchored by SpaceX and Tesla. SpaceX represents Musk’s single most valuable asset, with his 42% stake in the private space company estimated at roughly $336 billion.
Tesla ranks second among Musk’s holdings, as he owns about 12% of the EV maker’s common stock, which is worth approximately $307 billion.
Over the past year, Musk crossed a series of historic milestones, becoming the first person ever worth $500 billion, $600 billion, and $700 billion. He also widened his lead over the world’s second-richest individual, Larry Page, by more than $500 billion.
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Tesla Cybercab sighting confirms one highly requested feature
The feature will likely allow the Cybercab to continue operating even in conditions when its cameras could be covered with dust, mud, or road grime.
A recent sighting of Tesla’s Cybercab prototype in Chicago appears to confirm a long-requested feature for the autonomous two-seater.
The feature will likely allow the Cybercab to continue operating even in conditions when its cameras could be covered with dust, mud, or road grime.
The Cybercab’s camera washer
The Cybercab prototype in question was sighted in Chicago, and its image was shared widely on social media. While the autonomous two-seater itself was visibly dirty, its rear camera area stood out as noticeably cleaner than the rest of the car. Traces of water were also visible on the trunk. This suggested that the Cybercab is equipped with a rear camera washer.
As noted by Model Y owner and industry watcher Sawyer Merritt, a rear camera washer is a feature many Tesla owners have requested for years, particularly in snowy or wet regions where camera obstruction can affect visibility and the performance of systems like Full Self-Driving (FSD).
While only the rear camera washer was clearly visible, the sighting raises the possibility that Tesla may equip the Cybercab’s other external cameras with similar cleaning systems. Given the vehicle’s fully autonomous design, redundant visibility safeguards would be a logical inclusion.
The Cybercab in Tesla’s autonomous world
The Cybercab is Tesla’s first purpose-built autonomous ride-hailing vehicle, and it is expected to enter production later this year. The vehicle was unveiled in October 2024 at the “We, Robot” event in Los Angeles, and it is expected to be a major growth driver for Tesla as it continues its transition toward an AI- and robotics-focused company. The Cybercab will not include a steering wheel or pedals and is intended to carry one or two passengers per trip, a decision Tesla says reflects real-world ride-hailing usage data.
The Cybercab is also expected to feature in-vehicle entertainment through its center touchscreen, wireless charging, and other rider-focused amenities. Musk has also hinted that the vehicle includes far more innovation than is immediately apparent, stating on X that “there is so much to this car that is not obvious on the surface.”
Tesla Model Y dominated China’s NEV sales in December 2025
Elon Musk’s net worth is nearing $800 billion, and it’s no small part due to xAI
