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SpaceX is building Starship’s first orbital-class booster at a breakneck pace
Within the last week, SpaceX’s South Texas Starship factory appears to have kicked things into high gear and are now assembling the first orbital-class Super Heavy booster prototype at a breakneck pace.
While the assembly of the Super Heavy known as Booster 4 (B4) wasn’t too dissimilar to what CEO Elon Musk described as a “very hard” build of Booster 3 up to last week, work on the rocket has visibly accelerated. Since January 2020, the process of building Starships and Super Heavy boosters has been fairly simple. Both onsite and offsite, raw materials (mostly sheet steel) are cut, bent, and welded into relatively small parts that then make their way to (or around) Boca Chica by truck, forklift, or crane.
With the help of jigs and good amount of automation, the resulting hardware is then welded together to form domes, header tanks, transfer tubes, tank barrels, flaps, and more. Once subassembly is complete, those integrated rocket sections are reinforced with stringers, ribs, and baffles and outfitted with mechanisms, hardpoints, brackets, plumbing, and more. Finally, final assembly – better known as stacking and by far the most visible step – can begin and technicians stack each of those premade segments on top of each other to form a complete Starship or Super Heavy.
While part fabrication and subassembly integration take weeks or months on their own, those earlier steps can be done concurrently, meaning that SpaceX can prepare sections for several different ships and boosters at the same time. For the last six or so months, at any given moment, SpaceX has had 40-60+ rings in work as part of 15-20+ different ring ‘sections’ visible all across Starbase.
Respectively, each Starship and Super Heavy booster require 20 and 36 rings apiece, while each of the propellant storage tanks SpaceX itself is building for the rocket’s first orbital launch pad require 12-15. All told, SpaceX usually has a combination of around 3-5 ships, boosters, and GSE tanks in some stage of assembly. Unsurprisingly, some assembly tasks are harder than others and building the first in a series of prototypes has almost invariably taken far longer than building those that follow.
Booster 3 Booster 4 LOx tank start May 20th July 16th LOx tank finish June 18th July 30th CH4 tank start June 24th July 28th CH4 tank finish June 27th July 29th Final stack June 29th Aug 1st?
In that sense, it’s not a huge surprise that SpaceX’s Booster 4 assembly has quickly surpassed the pace set with Booster 3 less than a month earlier. SpaceX began stacking Super Heavy B3 around May 20th, starting with the rocket’s aft liquid oxygen (LOx) tank. Five separate stacks are required to turn the LOx tank’s 23 steel rings into a single structure – a process that took SpaceX about a month with Booster 3.
Booster 3 methane (CH4) tank assembly began a few days after the LOx tank’s completion but proceeded far more quickly, wrapping up just a few days later. Two days after that, those two tank sections were then mated and welded together to complete Booster 3’s full ~65m (~210 ft) tall airframe.
Now, just four weeks after Booster 3 was rolled to the launch pad for proof and static fire testing, Super Heavy Booster 4 is well on its way to reaching its full ~65m height almost twice as quickly. With work beginning around July 16th, B4’s oxygen tank is now just missing an (extremely complex) engine section and the booster’s methane tank was stacked to completion – 13 rings tall – in less than two days. That leaves SpaceX’s first potentially flightworthy, orbital-class Super Heavy booster just two stacks away from completion less than two weeks after its assembly began.
If SpaceX can sustain that pace for another few days, Booster 4 assembly will be the fastest of any full-height prototype ever built at Starbase, most of which have been Starship prototypes that are half to about three quarters the size of Super Heavy.
Tesla has updated its Robotaxi app so riders can pick which vehicle they want before they book. The latest in-app screens now show two options side by side: the two-seat Cybercab and the four-seat Model Y.
A screenshot circulating Thursday shows the change in practice. In Austin, a rider could choose a gold Cybercab for two people or a Model Y for four. Tesla’s updated description calls Cybercab “our first purpose-built autonomous vehicle,” designed for safety, accessibility, and comfort, and says the lineup is available only through the Robotaxi app.
Tesla has updated their Robotaxi page in the App Store. You’ll be able to select if you want a Cybercab or Model Y Robotaxi.
“Our Robotaxi vehicle lineup now includes Cybercab, our first purpose-built autonomous vehicle. Designed for safety, accessibility and comfort, Cybercab… pic.twitter.com/Jff4klilDr
— Sawyer Merritt (@SawyerMerritt) September 3, 2026
The distinction is more than cosmetic, and it’s important to note that Robotaxi refers to the platform, while Cybercab refers to a vehicle.
Model Y Robotaxis have carried the service since it opened in Austin in mid-2025 and later expanded to Dallas, Houston, and parts of Florida. Those vehicles are converted production SUVs that still have steering wheels and pedals.
Cybercab is different. It has no driver controls, butterfly doors, a low seat height meant to work with wheelchairs, extra trunk space for assistive devices, and braille on the handles. Tesla has registered dozens of the two-seaters with Texas regulators in the days leading up to its September 3 Austin event.
Giving riders a choice lets Tesla match the vehicle to the trip. Most rides involve one or two people, which is where Cybercab is meant to be cheaper and more efficient to operate. Groups of three or four, or anyone who needs more space, can still request a Model Y.
The same app handles booking, payment, cabin settings, and, on Cybercab, features such as phone-based door opening and in-cabin voice controls.
The update does not mean every city suddenly has both cars available. Cybercab support is listed for Austin first, and the purpose-built fleet is still small compared with the existing Model Y roster. Even so, the app change marks a shift from a single-vehicle pilot to a mixed fleet.
Riders can now choose between the compact, purpose-built robotaxi and the familiar SUV that launched the service.
Tesla Cybercab sightings are broadening far and wide, well outside of downtown Austin, Texas, with autonomy in focus as the company plans to launch the all-electric, two-seater this evening in the Lone Star State.
Tesla is set to launch Cybercab to a small group of people this evening in a dedicated event in Austin, Texas. Public details on the event are relatively slim.
However, Tesla’s focus on Cybercab falls well outside of the downtown Austin area and is expanding well across the United States as things continue to move quickly with the company’s autonomous efforts in 2026. Today, various images of Cybercab fleets in interesting locations have started to circulate.
The most notable is a fleet of at least 20 Cybercabs at Miami International Airport in Florida. Spotted last night, the fleet is expansive and is indicative of a looming release of Cybercabs once regulatory boxes are checked off.
Tesla has already been operating the Robotaxi platform in Miami for several months, but this Cybercab fleet at the airport could be joining the ride-hailing platform as approvals arrive:
20+ Cybercabs spotted near Miami international airport. pic.twitter.com/ORLsw8yFhf
— Sawyer Merritt (@SawyerMerritt) September 3, 2026
Another fleet of Cybercabs was spotted at the Devon, PA showroom just outside of Philadelphia. We have seen several Cybercab units testing around the Philadelphia Metro Area, which is interesting considering Tesla does not have any active Robotaxi geofence in Pennsylvania.
Cybercab at the Devon location in PA has multiplied over the weekend. Seeing a few more test vehicles in the lot 👀 pic.twitter.com/DhJT4P1EkU
— Billy (@billykyle) August 22, 2026
Philadelphia would be an ideal location to test ride-hailing due to its dense tourist population, large, sprawling city layout, and to compete with other ride-hailing companies that operate in the city.
Expansive fleets of Cybercabs will be popping up in and around major cities throughout the rest of the year, if we were betting on it. Tesla has made it obvious that the Cybercab rollout will be aggressive and fast-paced, but within reason. Tesla is still prioritizing safety, so these testing phases will likely go on for some period of time before more members of the public are able to snag a Cybercab for a personal chariot.
The Tesla Model Y L is arguably the most hyped trim of the all-electric crossover, other than the Performance configuration that comes with white-knuckle speed and sports car-level handling.
However, it is not all perfect. Tesla owners in China who took delivery of the Model Y L, denoted with an L to highlight its longer wheelbase, are experiencing what they are referring to as “collapsing” of the rear wheels, as suspension issues appear to be an issue with some of the builds.
🚨 Model Y L owners in China report rear suspension sag
• Six-seat long-wheelbase Y. Shanghai. On sale since August 2025
• Owners say the rear tire-to-arch gap shrinks after mileage or a full load. Some cases after about 9,000 km loaded. Others near 30,000 km
• Tesla service… pic.twitter.com/Lr6i5Tbi07— Joe Hansen (@joehansen) September 1, 2026
The gap between the wheel arch and tire has narrowed to the point that “not even a single finger” could fit, according to a report from Car News China. The failures are not tied to a specific mileage, as one owner said that after just 9,000 kilometers (5,600 miles), they noticed the suspension issue when their car was fully loaded.
Another one had the issue at 30,000 kilometers (18,640 miles) and noticed that the wheel gap shrank to two fingers, so not as drastic as the person who reported a similar issue at 9,000 km.
Tesla Model Y L is gaining momentum in China’s premium segment
Along with the visual recognition of the issue, others are saying the sagging is causing abnormal wear on the inside of the tires. Extra weight and instant torque already provide additional stress on the tires in electric vehicles during normal operation, so it is no surprise that this is another complaint.
There has been no recall issued by Tesla, and the company has not yet publicly acknowledged the issue.
Some are suggesting that owners use a “finger test” to self-diagnose whether there is an issue with the suspension. There should be four fingers between the tire and the wheel well; anything less than that starts to get dicey.
Tesla Robotaxi riders will face the best dilemma when booking a ride
Tesla Cybercab sightings broaden well outside of Austin with autonomy in focus
