Lifestyle
Charging a Tesla Model S Might Be Costing More Than You Think
When you fill up a normal ICE car you know exactly what your costs are for the fuel. With an electric vehicle it is not that simple. There is a charging efficiency factor that comes into play which means that the reported amount of energy used could be understated and lower than the actual energy used. In a previous post I wrote about installing an EKM Digital Submeter on my NEMA 14-50 outlet to measure actual power usage of the Model S against the reported power displayed on the driver’s digital dash display. A month later and armed with more data, the energy loss I’m seeing is larger than I had originally expected.
Test Setup
I charge at home 99% of the time and in the last three months I’ve logged 7,500+ miles driven, one trip to the Supercharger and two visits to the Tesla store’s High Power Wall Connector. I have a professionally installed NEMA 14-50 outlet at home. I’m using the factory supplied Universal Mobile Connector (UMC) as the cable between the outlet and the car. An EKM digital sub meter measures actual draw from the outlet and is accurate to within 1% and does not add any measurable load of its own.
Methodology
On the “anniversary date” of taking delivery of my Model S I recorded all of the pertinent info that was displayed before resetting the Trip A meter. Before driving the next day I record the reading on the EKM meter. That way I’ve got the mileage and the Tesla reported power usage over the period driven. This process will let me see a bunch of information that I plan on tracking over time, as follows:
- Monthly miles driven
- Monthly kWh used as reported by the Model S
- Monthly kWh used as reported by the EKM meter
- Monthly Average energy used
I plan on using this information to look at how average energy used changes as the months/temperature changes and perhaps as the Model S gets more miles on it. While I don’t drive consistently on any given day (test drives, special trips and the like), the numbers will average out and my driving style is not likely to change much after 30 years of driving (yeah I’m getting old but the Model S makes me feel young again!). I also drive pretty consistent patterns of commuting with a lot of miles to the same places which helps average out the special trips to locations with different terrain/conditions. Basically, while the conditions aren’t perfectly stable over time, the averages and data from this real world testing will be pretty accurate.
The Data
The last period (6/21 – 7/21) was my first full period with both the car and the EKM meter. A month of driving and charging, especially with the miles and kWh’s involved is a decent period over which to look at the results versus the 2 days from my prior blog post. Here’s the data:
In the above table you can see that the Model S reported 728 kWh used during the period but the meter reported 894 kWh used. This means my charging efficiency is only about 82% and electric usage (and cost) is 23% higher than I may have expected based on the readings the Model S provides. For that month this is an extra $26 of charging cost which is a small number but a notable percentage of the total. The good news is that even using this larger kWh number, the savings versus driving my old ICE car for energy alone comes in at $334 — I’m saving $334/month in gas driving my Model S!
Summary
Research suggests that an average charging efficiency loss ranges between 10-12%. Over this one month period of over 2,400 miles I'm seeing an 23% loss using the standard home charging setup that Tesla recommends. Many people quote an 85% charge efficiency for Tesla, and Tesla's own charging calculator appears to assume a 91% charging efficiency which is quite different than the 82% actual charge efficiency I've measured and significantly worse than the average industry charging efficiency. It would be great to see another Model S owner do a similar test using the HPWC setup at home and see if they get results similar to what Tesla is providing. I'd love to do the test but I'm not quite ready to shell out $1,200 plus electrician costs to get that data -- assuming a cost of about $3,000 all in it would take me over 20 years to break even assuming the HPWC improves my efficiency by 10%. From the results above, my conclusion is that the Model S charging efficiency using the standard home setup is 5-10% worse than other EVs on the market.
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Elon Musk
Elon Musk drops a surprise update on Boring Company’s next big dig
Musk says Boring Company could shrink the Austin to San Antonio drive to just minutes.
Elon Musk says The Boring Company is working on what he called “a simple, precursor Hyperloop” tunnel connecting Austin and San Antonio, targeting speeds above 200 mph and cutting a drive that can take up to two and a half hours down to a consistent under 30 minutes. Musk posted the idea on X Sunday, in a reply to a repost of an AI generated video imagining a science fiction future with human colonies on other worlds, which he shared with the line “This is the future we shall bring into being.”
This is the future we shall bring into being pic.twitter.com/8aD0w8MDVc
— Elon Musk (@elonmusk) September 20, 2026
The Boring Company’s own account picked up the idea in the same thread, adding a detail about how the trip would actually work: “Because Loop/Hyperloop is express (i.e. no intermediate stops), one could travel from an Austin parking lot to a favorite San Antonio restaurant in about 30 minutes. As long as they both have Loop stations.” That framing ties the proposed intercity link to the same station model the company already runs in Las Vegas, where riders enter the tunnel network through small, garage style stops rather than one central terminal.
This is not the company’s first run at the Austin to San Antonio corridor. Boring Company floated tunnels between the two cities as far back as 2021, and later competed for a separate San Antonio Loop project tied to the airport before that specific bid stalled. Pitches for tunnels in Chicago, Los Angeles, and a New York to Washington corridor have followed a similar pattern of big announcement without a shovel in the ground.
What is different this time is the balance sheet, especially since The Boring Company closed a 3 billion dollar funding round led by investors in the United Arab Emirates earlier this month at a valuation near 23 billion dollars, giving the tunneling company more capital to chase speculative projects than it had during its earlier Texas pitches. The company is also mid-build on two other intercity systems it has actually broken ground on, inc;luding a Nashville tunnel linking downtown to the airport, where a second boring machine finished commissioning in June, and its Las Vegas network, where the station count keeps climbing on paper faster than tunnels get dug.
That gap between announcement and execution is the reason to treat Sunday’s post as an opening bid rather than a project. A tunnel spanning roughly 80 miles between two metro areas, running at speeds Boring Company has not demonstrated over any real distance, would dwarf anything the company has built. For now, the Austin to San Antonio Hyperloop exists as a caption under an AI generated space video.
Elon Musk
Tesla eyes supply partners for Optimus mass production
Tesla certified three Chinese suppliers for Optimus mass production, signaling its robot timeline is accelerating.
Tesla’s robotics team traveled to Ningbo, in China’s Zhejiang province, on September 16 and spent the following day auditing component suppliers for Optimus, according to a Bloomberg report cited by RobotAIGeek. The visit moved three manufacturers from provisional status to certified mass production partners: Tuopu Group, which handles actuators and chassis components, Ningbo Joyson Electronic, a sensor supplier, and Zhejiang Sanhua Intelligent Controls, which builds thermal management systems. All three already supply parts to Tesla’s electric vehicles, and the audit reportedly came with fresh orders that supply chain reports put at an initial batch of roughly 5,000 units.
Tuopu, Joyson, and Sanhua built their manufacturing base serving the automotive industry, where tolerances and volume requirements are already close to what a mass produced humanoid robot demands. Sanhua in particular has history here. Teslarati reported last October that the company had received a roughly $685 million order for linear actuators tied to Optimus, a volume industry watchers estimated could cover around 180,000 robots once production ramped.
Supply chain reports tied to this week’s audit put Tesla’s near term production goal at about 1,000 Optimus units a week by late September, rising to 2,000 to 2,500 units a week by the end of the year. That pace would put real weight behind the timeline Tesla has been building toward since May, when it wound down Model S and Model X production at Fremont to convert that floor space into a dedicated Optimus line targeting one million units annually. JPMorgan analysts who toured the factory in August confirmed the conversion took roughly four months, a pace Musk has called unprecedented for a facility that size.
New drone video shows Tesla’s Optimus Factory reaching a turning point
Fremont is only the first phase. A second, larger Optimus plant is rising at Gigafactory Texas, where drone footage shared by Joe Tegtmeyer last week showed the structural steel nearing completion on the north end of the building. Tesla has said that facility is meant to eventually support production of up to 10 million units a year, though volume output there is not expected before 2027.
Commercial sales of Optimus are still targeted for the second half of 2027, but production is expected to start well before then. JPMorgan analyst Rajat Gupta has said Tesla’s “Optimus Academy” program, which uses early units to collect real world training data inside Tesla’s own facilities, is expected to be running later this year. Bloomberg Intelligence analyst Ian Ma described the Ningbo audits as “a positive commercialization signal for China’s humanoid supply chain,” noting that sentiment could improve further if the visit leads to confirmed supplier nominations and larger orders. The Solactive China Humanoid Robotics Index rose about 1.4% on the news, though it remains down roughly 30% for the year.
Elon Musk
Tesla primes Cybercabs for 4K streaming and high bandwidth gaming with Starlink integration
Tesla is now shipping Cybercabs from Giga Texas with Starlink hardware built in as standard.
Tesla’s Cybercabs are now leaving Gigafactory Texas with Starlink hardware on the rear hatch in significant numbers, according to drone footage captured Tuesday by longtime Austin drone observer Joe Tegtmeyer. Production at the factory ramped back up after the Labor Day weekend, and his flyover of the outbound lot showed rows of gold Cybercabs alongside Model Y Long Wheelbase units, many carrying the satellite module for the first time as standard equipment rather than a one off retrofit.
Giga Texas today is busy with production coming back up following the long weekend. Of interest today in the outbound lot is the appearance of hundreds of Mode; YL’s and many more Cybercabs and for the 1st time equipped with the Starlink module one the hatch in big numbers.
At… pic.twitter.com/G9yl6s51m4
— Joe Tegtmeyer 🚀 🤠🛸😎 (@JoeTegtmeyer) September 8, 2026
Tesla first showed Starlink built into an actual Cybercab on August 10, when the Robotaxi account posted images of a single gold unit with the antenna integrated into the roofline above the taillights and called it the first Cybercab with Starlink integration. That followed a July reveal where Tesla and Starlink jointly posted a cutaway diagram of the antenna placement without a working vehicle to back it up. Ashok Elluswamy, Tesla’s VP of AI software, said at the time that the connection isn’t required for the car to drive itself. It exists mainly for navigation, customer service and keeping tabs on the fleet.
Musk has made a different case in public. During Tesla’s Q2 earnings call, he said the company can’t afford robotaxis stranded in what he called “Bermuda Triangles of lack of cellular connectivity,” and he separately claimed on X that Starlink will eventually reach every Tesla built, calling it the only way to deliver high bandwidth to billions of vehicles. He has also pitched the antenna as an entertainment upgrade, telling riders they would be able to stream 4K video or play games during a trip.
The rollout has moved fast since. Robotaxi service opened to the public in Austin on September 3, and Cybercabs had already been spotted with Starlink hardware in Houston and near Miami International Airport in the weeks before Tuesday’s factory footage showed the module shipping at volume rather than on scattered test units. Whether the satellite link earns its keep is still an open question. Tesla’s unsupervised service currently runs in dense metro geofences in Texas and Florida, markets where cellular coverage is already strong, which is not where the rural dead zones Musk describes tend to show up.