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.
RELATED: Comparing Tesla battery technology against the competition
Lifestyle
Tesla Cybercab and Robotaxi’s real advantage won’t be the ride service
For a century, the car has asked the same thing of its owner, which is basically to pay attention. Even the best ride-hailing app like Uber or Lyft only moved the problem into someone else’s hands. You stopped driving, but you still sat in a stranger’s car, while half listening, and wondering whether to take a phone call in the car without being rude. The Cybercab has no wheel, no pedals and no driver. With Grok @bot now live inside it, it becomes something else entirely, and I think that matters more than the fleet count that everyone is tracking.
Grok @bot is an agent, not a voice assistant. A rider signs in once, and from then on can say what they need and watch it happen. Order dinner from a favorite restaurant. Fill the grocery cart. Move money, answer email, adjust a calendar, push a work project forward. Tesla engineer Yun-Ta Tsai confirmed it is enabled across every Cybercab and the rest of the Model Y fleet, and Tesla’s own pitch is that Full Self-Driving handles the commute while Grok handles the errands.
Think about what that does to a thirty minute ride. Uber sells you a trip, while Waymo sells you the same trip in a more private setting. Tesla is selling the thirty minutes themselves, returned to you with an assistant attached. Errands that used to eat a Saturday get done between pickup and drop off. The ride stops being dead time between two places and becomes a place of its own.
Tesla integrates Grok Bot into its vehicles for the ultimate personal assistant
Best of all, your Bots follow you into any Cybercab, and presumably your own Tesla, then logs you out automatically when you step out. Anyone can bolt a chatbot onto a screen, but much harder to own the vehicle, the autonomy stack and the assistant at once. It also quietly ties SpaceX’s Super Intelligence business to Tesla’s fleet, after Tesla converted its xAI stake into SpaceX equity. The relationship between those two companies is getting harder to describe as separate.
This is also where the hard questions start, because an agent that can spend your money in a vehicle other people also ride in needs some answers. How does it handle a voice it shouldn’t trust? What gets recorded, who can see it, and for how long? What happens when a rider leaves halfway through a task?
If Tesla gets those answers right, the scoreboard changes. We have been counting Cybercabs and wait times. The more telling number may be what riders accomplish per trip. That is data almost no one else will ever have, and it is the real reason to watch Grok @bot.
What do you think? Leave me a comment.
Lifestyle
Tesla’s mirrorless Cybercab will give riders a visibility upgrade
Tesla engineer confirms Cybercab update letting riders pull up rear and repeater cameras on demand.
Tesla is working on a Cybercab update that would let passengers pull up the vehicle’s rear and side cameras on demand, and the request came straight from a rider.
The exchange played out on X late Friday. Cybercab rider Dan Burkland shared photos of the two-seater’s cabin screen after an evening ride, praised the UI team’s work, and left one request: let riders open the rear and repeater cameras whenever they want, “especially for peace of mind.” Tesla UI software engineer Evan (@CarCoder) answered with two words: “In development.”
The Tesla UI team absolutely crushed it with the infotainment software. Nicely done @CarCoder!
One feature request: Allow folks to pull up the rear & repeater cameras on demand. This would be great especially for peace of mind. https://t.co/mNAOSLx6pE
— Dan Burkland (@DBurkland) October 10, 2026
The idea fits a pattern Teslarati has tracked since public rides began. Days after paid Cybercab service opened in Austin, Tesla sent riders a survey that asked them to rate the touchscreen, the app and the cabin, and to pick the features they wanted most. We reported on that survey in September, and a camera view is the kind of small software change Tesla can push quickly if riders keep asking.
It also speaks to something unique about the vehicle. With no steering wheel, no pedals and no driver, passengers have no mirror to check and no way to see behind them. The hardware is clearly built for camera awareness, from the repeater cameras to the rear camera. Letting a passenger look through those same cameras would give a nervous first time rider a way to confirm what is around the car.
The timing matters because the fleet is growing fast. Tesla’s Robotaxi account said on Saturday that more than 300 Cybercabs are now serving Austin, an eightfold increase in 30 days, and Tesla AI chief Ashok Elluswamy named Dallas as the next city. More cars and more cities mean more people riding in a driverless vehicle for the first time, which is exactly when small trust features carry weight.
For now, the feature is confirmed only as in development. If Tesla follows its usual pattern with Cybercab software, riders could see it appear in a point release without any announcement, and Teslarati will watch for it.
Elon Musk
Elon Musk’s surprise addition to the X Takeover lineup has fans talking
Elon Musk will join Saturday’s X Takeover at Giga Texas for a live virtual interview.
Elon Musk will join X Takeover at Giga Texas on Saturday for a live virtual interview, according to Sawyer Merritt, who shared the news late Thursday. Musk will not be on stage in Austin. The conversation is set to stream for free on the @teslaownersSV account on X.
Organizers had kept expectations in check. In a September update, Tesla Owners Silicon Valley said Musk had appeared at the event twice before but was not promising a third appearance, even as fans hoped he would walk the Giga Texas grounds in person. A virtual spot matches 2024, when Musk gave a surprise interview of about an hour to the crowd in San Luis Obispo, as Teslarati reported at the time.
Wasn’t expecting this 🫡
— Tesla Owners Silicon Valley (@teslaownersSV) October 9, 2026
This year’s edition is a first in several ways. It is the first X Takeover held outside California and the first at a Tesla facility, with tickets selling out in eight days. Tesla provides the venue, but the event is produced independently by Tesla Owners Silicon Valley. The main event runs from 10 a.m. to 6 p.m. CT, followed by a drone and light show at 9 p.m. Maye Musk is the keynote speaker, Franz von Holzhausen is set for a virtual keynote, and Nicki Minaj is the special guest. Joe Tegtmeyer, whose drone footage Teslarati used to track the Optimus factory steel frame at Giga Texas, is also on the speaker list.
Musk’s interview topics have not been revealed, but the backdrop is busy. Tesla doubled its Cybercab fleet in Austin in late September, and last week Musk explained why Robotaxi hours only moved from 10 p.m. to 11 p.m.. Merritt also reported Thursday that Texas DMV records now show 319 registered Cybercabs, up from 169. NHTSA’s deadline for Tesla’s sworn answers on Cybercab certification is October 30, and Tesla reports third quarter earnings on October 21.
Fans who cannot make it to Austin can watch the livestream on X. Musk tends to say more in unscripted settings than he does in prepared remarks, which is the reason this one is worth having open on Saturday.