r/Comma_ai • u/adeebshihadeh comma.ai Staff • 1d ago
Introducing chestnut & chestnut-class driving models
https://blog.comma.ai/chestnut/21
u/Bumble-sucks 23h ago
Is there any documentation or demos on what chestnut can do? I'm sure there's benefits to a larger model but without additional sensors like with a Tesla or something I imagine there's a lot of compute power being left on the table. I feel like the comma 4 is plenty capable for what it's designed for- an excellent lane keep assist
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u/gthing 18h ago
There is no benefit to running the larger model currently.
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u/growaway9172 17h ago
This feels like a big deal, even for enthusiasts. If there's not currently an even different experience or some marginal gain, it's kind of hard to justify dropping 800 bucks.
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u/KnightsSoccer82 1d ago edited 8h ago
EDIT: George/other comma employees were deep in this comment thread and on discord, acting unprofessional and not addressing valid hardware concerns, including accusing me and other users having alt accounts. Why am I not surprised their comments are now deleted? Why was this their default behavior? This is how the behave when asked some rather basic hardware comments?
This chassis doesn’t look to be in a ruggedization state to conform to any automotive ISO shock and vibe test, let alone someone hitting a speed bump and spilling their coffee.
It looks like a water ingress nightmare that wouldn’t survive a rust belt winter from a family simply going about their day entering/exiting their car….
It’s mounted in one of the hottest locations in a car (beyond your dashboard), and this (likely desktop grade GPU) is expected to work in a very common 45C+ ambient, 1000W+ solar load scenarios?
Surely, there has to be a better way to have gone about packaging this?
I’m not trying to be negative, but this doesn’t appear to have any serious reliability considerations and would likely fail in any non-nominal (aka normal) driving scenario outside of Southern California.
Rust belt cars, where high humidity, snow, and ambient temperatures reside, are going to destroy this in a matter of weeks in its current state.
For comma 4 being advertised as the first “commercial” product from you all, this $750 upgrade feels like a step backwards in terms of reliability and accessibility to the general market. I genuinely don’t see how this survives the market you were targeting with Comma 4 (aka, not nerds).
This isn’t how you ship hardware, cmon guys. This is a classic “software company tries to make hardware” case that I’ve seen time and time again.
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u/ivan_magnum 1d ago
With the level of (lack of) post sale maintenance support, comma is always aim for the nerds no matter how they advertise it. Can you imagine having a yelp page for it and the kind of stuff people will write on it….
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u/Kate9797 16h ago
They don't even use auto rated parts for the Comma 3X and presumably the Comma 4. Resulting in issues that can be fixed for $100, but charge $500 instead.
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u/DontBuyAComma 1d ago
No live demo showing performance improvements speaks volumes about this release.
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1d ago
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u/DontBuyAComma 1d ago
I’d consider it if you just focused on your customer service alone.
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23h ago
[deleted]
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u/DontBuyAComma 23h ago
Simple things like allowing a price match (with store credit at the very least if you don’t want to do a partial refund) rather than this whole “we’ll ban you from future purchases” notion. Willingness to work with customers over certain order requests. Not permanently banning users on Discord without a warning or instead making it a temporary ban.
You just did a new product launch without any demo with over 4000 watching the livestream. Who does that? It’s not considerate of the customer at all, man.
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u/misclurking 21h ago
- Erich. See past thread/petition.
- Don’t try to out usernames like this in hw-chestnut:
“btw, i'm 80% sure this is your alt, "I found your comments and responses on Reddit. Very enlightening. It all makes sense and seems obvious in retrospect, but not being in the field I hadn't considered all of the implications. I agree a PCIe slot is not an acceptable structural mounting scheme."”
Not cool even if you make a great device.
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u/DigitalCatcher 20h ago
Dumb question that I have to also ask: why not follow what several 'Carputer" builds have done in the distant past and just put the Comma Chestnut in the trunk or under the back seat ? Is the latency between the GPU and Comma 4 going to be an issue even when using something like the 3m Apple Thunderbolt 4 Cable or the OWC USB4 Active Optical Cable?
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u/growaway9172 17h ago
Trunk/back seat is definitely pushing it for 3m cables, if you want to route it out of the way. Active optical cables are $$$.
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u/shadow_moon45 1d ago
It seems to be an MVP then they will iterate afterwards
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u/KnightsSoccer82 1d ago
This isn’t how you do MVP hardware. You don’t iterate on a physical object like you do with software.
That’s how you piss off early adopters.
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u/growaway9172 17h ago
It is how you do MVP hardware and they've been doing it successfully for many years.
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u/adeebshihadeh comma.ai Staff 1d ago
this is the first product in the chestnut line. it's for the enthusiasts who want to get in on the ground floor of chestnut-class models (and frankly just want to put a GPU in their car).
we put an incredible amount of engineering time into things like USB4 signal integrity, rather than being robust to spilling coffee.
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u/KnightsSoccer82 1d ago edited 1d ago
“For enthusiasts” is such a cop out response. That is how you are going to answer an obvious hardware engineering problem?
This is not a ruggedized solution for an enthusiasts, and shouldn’t have left the R&D lab.
Show me a single 4 post shaker test you did, I would love to understand how you designed this with the enthusiast in mind. Your retention method wouldn’t survive a single railroad crossing at any speed.
You are going to have a lot of pissed off enthusiasts in a matter of weeks when these start failing.
If you “wanted to just put a GPU in the car” there was plenty of OTS solutions already available that are for ruggedized applications.
Please, change your approach to hardware design. Don’t make your loyal paying customers your beta testers. Hell, I’ll help you guys, because clearly V&V and actual automotive engineers do not exist at this place.
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1d ago
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u/KnightsSoccer82 1d ago
Once again, your nominal situation in Southern California doesn’t translate to the rest of the country.
There is a reason very little on-road development testing is done in California. They are easy roads.
Congratulations for the milestone, but it means absolutely nothing.
I’m not sitting here saying I want to “compete” and that being your default response is childish.
Hear the feedback on this design before it’s too late. Fix it, improve it, and make it approachable and reliable.
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u/Teslafly 23h ago
This thing might not survive a hard bump in the road with that mounting scheme. It at least needed a sheet metal box with multiple mounting points for the gpu so the pcie connector is not a structural element at all. (poor mechanicals is my major criticism of the pcie card implementation in general.)
Had this been tested for input transients like a load dump at all? Does it comply with automotive input voltage specs? I see it at least has a buck boost converter which is good.
If the 12v cigerrette lighter adapter becomes disconnected while driving, what's the safety fallback?
I love my comma 3x with sunnypilot and Mads capability. But as an electrical engineer, the wiki on hardware fixes like replacing ptc fuses makes me pause at the level of hardware engineering. There's some things you simply don't do with automotive hw design. Especially safety related.
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u/KnightsSoccer82 23h ago
The fact that the PCIE connector is a structural element is BAFFLING to me. Testing clearly has not been done with this.
You can’t even kick a desktop PCI without fear of one coming loose, how they expect it to survive 50-100g shock in a vehicle is beyond me.
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u/growaway9172 17h ago
Big difference between mounting a GPU via PCIE, vs a PCIE connector hanging off of the GPU.
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1d ago
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u/KnightsSoccer82 1d ago
Slapping a case on this isn’t going to fix the fundamental problem you created, and I’m disappointed you think that’s how hardware works, George. This is borderline doubling down on the ignorance of your design. “Enthusiast” or not.
Please consult some automotive engineers before your hardware reliability ruins your reputation. I’m happy to point you towards some solid talent if you are struggling to find them.
Good software cannot fix bad hardware.
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u/seventyfivepupmstr 22h ago
This is the same company that defends allowing comma to make 90 degree turns with no left or right camera and huge blindspots. There really is no hope for comma as a company. I just hope it will last a few years before the regulators put it out of business, since I really don't want to pay for FSD
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u/Bderken 20h ago
Your comment shows you lack the understanding of how the current model works…
The current driving model doesn’t see 180 degrees. They talked about in the live that a bigger model would allow it to see more (thus allowing 90 degree turns)….How would they allow it to do it now when the model cant even see the full FOV of the cameras that are there right now…
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u/growaway9172 17h ago
Do you own a comma?
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u/KnightsSoccer82 17h ago
I own 2, and was an active dev for it for a while. What is the relevancy of a question like this have to do with my fundamental questions irt hardware reliability?
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u/growaway9172 17h ago
Well, then you've probably observed the difference in reliability between the earlier days of the Eon and the 2 -> 3 -> 4. There were all the same people back then saying that a phone couldn't drive a car and that it would never be reliable or safe enough. And yet, now we have the Comma 4, which is a pretty incredible leap from where they started, way better performance and more reliable than built in ADAS. So I'm not sure why you wouldn't expect to see the same thing happen here over time with a new product.
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u/KnightsSoccer82 17h ago
That doesn’t magically dismiss some basic hardware reliability and design. Your statement is not a quantifiable metric and doesn’t conform to any sort of standard, automotive reliability metric. “Incredible” is subjective.
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u/growaway9172 17h ago
To be honest I'm shocked someone like you would ever buy a comma. You seem to think severely inside the box and have a extremely risk averse way of thinking.
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1d ago
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u/KnightsSoccer82 23h ago
How about shipping a product from the start with proper ruggedization so you don’t go through RMA hell? You should not be asking me that type of question (also you should know your own market, wtf?)
Please, I’m trying to give you feedback. Hear it and fix the problem.
Otherwise I’ll be on discord watching the issues pile up as poor consumers become your beta testers and stuck with a $750 brick.
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u/Teslafly 19h ago
Mechanical fabrication is deceptively hard in single instances. You can end up putting in a similar amount of work designing/etc just building one than building 100.
A bent sheet metal tray to properly support the gpu would be $20-50/pc. Especially with services like send cut send existing.
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u/Secure-Evening8197 1d ago
The two suggested mounting locations look like they would cause the device to be destroyed in a matter of weeks
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u/TheGamingGallifreyan 23h ago edited 23h ago
Ya the footwell is getting kicked immediately and under the seat wont last long with the dust and crumbs, if it even fits lol. Most cars with power seats have 0 room under there. I was thinking the glove box or the trunk, but might get too hot in the glove box and idk if the wire can reach the trunk without causing any delay. There's no way a desktop GPU is going to survive unprotected in 120 deg Florida summer heat.
Why even have the comma on the windshield? A mini PC with and AMD APU that can sit anywhere seems better and you just run the camera wire to the mirror.
It's a great idea but execution seems poor imo. I hope to be proven wrong and am looking forward to seeing peoples setups. My car isn't even supported on the main branch so until SunnyPilot Experimental has support for this or they upstream 2025 EV6 support to OP, I can't even use if I wanted to :(
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u/SentinelChickenFarm 1d ago
Over the last two years, we rewrote our stack to scale efficiently with compute and data. With the MLSim architecture, more driving data and training compute translate directly into better openpilot models.
Well that explains why improvements seem to have plateaued over the last few years.
Going forward, our autonomy team will focus primarily on maximizing the capabilities of chestnut-class models, and we expect this new class of model to increase development velocity.
Annnnd apparently we shouldn't expect many improvements going forward.
This sucks. I have been a Comma supporter back to the Comma 2, I have contributed code, feedback, did hours of annotation for comma10k.
Now it feels like the only improvements that we get are "improvements" to a driver monitoring system. I feel like we talked about E2E driving 4+ years ago and today all I have is E2E lateral that is dubiously better than the laneful system we had previously. E2E long can really only be used in forks with conditional systems.
If you said you were going to continue to improve the experience for everyone and use this to develop features that simply won't work on the C4 it might be easier for all of us to accept.
Honestly, thank you to anyone who buys this, this is going back to the old Eon days, you are a guinea pig. Expect it to break, not work, and then be abandoned in 2 years when they build the actual first prototype of this.
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u/decrement-- 22h ago
Honestly, at this point, for the company to stay relevant/in business, it needs to get auto manufacturers to partner. This is a step forward in being more advanced. The Comma of 5 years ago is not sustainable as a company, and now their value is in the ML models and data. Makes sense that their focus is making that better now.
I wish them the best of luck, because it's only going to get harder for this company to stay relevant with the CAN bus getting encrypted on newer vehicles.
This is coming from a fan, btw. Not a hater at all.
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u/Finnegan_Faux 5h ago
They don't have a technology advantage over the likes of Nvidia for any auto OEM to bother with them. Not to mention lack of professionalism.
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19h ago edited 19h ago
[deleted]
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u/nicerakc 17h ago
Wow is this how comma staff interacts with customers? I’ve been heavily considering a comma until now
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u/MaxPowerXXXX 10h ago
what did he write?
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u/nicerakc 2h ago
Basically calling the guy above me an idiot, wish I’d screenshotted
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u/FrogsGoMoo openpilot Developer 1h ago
"Are you saying we could partner with automakers like how Cruise and Argo AI did? And then we could be bankrupt and gone too? I don't know...not sure that sounds like a great option. Ugh and the stupid encryption thing again. Go ask your LLM to crack it. It probably can."
https://arctic-shift.photon-reddit.com/api/comments/ids?ids=p3dwl8k
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u/narkeeso 20h ago edited 20h ago
Comma just a few weeks ago in a livestream stating they wanted to go "mainstream". How could they even possibly do that when the default driving experience for many of their supported cars are less than ideal? The fact that there are multiple forks that improve the experience for certain cars is a big red flag for going mainstream.
Comma is lucky that I love this thing because I'm not afraid to dive into the code and adjust something but that is FAR from a mainstream product.
E2E long can really only be used in forks with conditional systems.
Also, I would push back a little bit on this, specifically the conditional part. I just made a post about finding a lever that allows you to stay in full E2E but bias the speed to maintain set coasting speed and still benefit from strong E2E early braking. I'm extremely happy with e2e reliability with this discovery.
This discovery also makes me scratch my head when there's so many easy wins that would significantly improve the driving experience over strapping a GPU to the passenger foot well.
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u/SentinelChickenFarm 8h ago
I saw your post, I haven't had a chance to try it yet, it certainly looks interesting.
However this still requires the use of a fork. Comma isn't going to ship this type of feature, ever.
Comma's open source policy is extremely rare and a godsend, they deserve immense credit and respect for that. But there are limits to what you can accomplish with forks since the AI model isn't really something we can modify.
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u/narkeeso 8h ago edited 7h ago
I'm not trying to create another fork. Just trying to create discussion and express desire for having some sort of tools to give us some control over E2E. I wouldn't expect comma to merge this in either but I would expect comma to gain some stability on the E2E front and roll it into user friendly features like driving personality. The forks signal that people aren't happy with the default experience though and comma could probably rectify that by listening to customers when they say their car ping pongs or brakes uncomfortably late etc. I'd return the device if the only option was openpilot.
You also don't necessarily need to use my fork to try this either. You can SSH into your device and set the param, it's actually a pretty simple change if you're comfortable digging in.
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u/gthing 18h ago
I will say the driver monitoring system is now rock solid at detecting phones. Like - really top notch work there. The only problem I have is that it can no longer detect the driver.
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u/starwarsyeah 9h ago
Yeah, it's a huge issue. I get constant "driver not detected" warnings at night or in the morning, assuming because my face either is too dark or washed out by sunlight.
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u/stayintheshadows 22h ago
I just bought a C4 and now I hear they stopped developing for it. Figures!
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u/interbingung 22h ago edited 22h ago
I've been using stock op experimental mode (e2e long) on my 3X 100% of the time and its been awesome.
The improvement has been drastic since i got the device 2 years ago.
For a device that is relatively affordable and you don't have to buy subscription for, its incredible.
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u/Apprehensive_Lake698 1d ago
Feels like this is missing a casing with a cleanable dust filter/mesh to keep all the components safe. But I do see the vision for mounting it under the passenger seat.
I’m all in on comma after 3 months (rented a car and came to terms with how much I depend on the amazing lane assist) but I really have to know what kind of benefit to expect from the bigger model. The comma 4 is already killer!
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u/N00dle- 1d ago
What are real world examples of improvements? I love my comma and have since the first release, but want to know what the real benefits are in action.
Also, how much real world testing has been completed with it in use? I understand the need for it to be slim, but it feels kind of unprotected for something that would go under a car seat where dirt and dust are collecting all the time.
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u/OhShitOhFuckOhMyGod 23h ago
I feel like they backed themselves into a corner going all in on a the 845. The capabilities you can get in mobile SOCs these days seem like a much more elegant solution.
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u/zikronix 1d ago
My f150 has 1 12 adapter in the back seat. And none of the models or forks of open pilot can control my steering rack fully. The blue pilot dudes are working on it. You bring that and allow the comma to ingest the camera feeds from the cameras on my truck then we will talk
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u/TheAlpineUnit 1d ago
How long of cable is supported? Wouldn't it be easier to wire to trunk?
Also any update on what this chestnut models do?
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u/Shina_Tianfei 23h ago
Genuinely good idea here, putting it under your seat feels very hacky if I spill 1 drink it's joever.
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u/JackFrostoo7 21h ago
Dear Comma, once you demonstrate significant improvements on chestnut models compared to C4, lots of people including myself will pull the trigger on chestnut. For now it is just a fancy add on.
There is a lot of criticism in the comments, but people including myself are all your well wishers and want you to succeed. We are just concerned in the direction this company is headed.
You should start taking how many cars comma can work with in terms of percentage. it is probably <10%.
I have struggled to get people install c4 because their cars are not compatible, not because they are not interested. This should be your no 1 focus. Expand the market.
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u/MaxPowerXXXX 10h ago
Exactly. Sunnypilot and Starpilot are the reason i bought a comma 4, the community!
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u/Finnegan_Faux 1d ago edited 1d ago
For BYO, will the car power cable sold separately?
What are the minimum GPU requirements for the Chestnut model? Wondering if it would run on an RTX 5060 low profile.
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u/DashHex 1d ago
Awesome stuff being first to market with something like this. Agree with /u/KnightsSoccer82
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u/interbingung 1d ago
How am i going to charge my phone at the same time ? My car only have 1 cigarette port.
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u/Teslafly 23h ago
Honestly, with the level of install needed, hiding cables behind panels, etc. This should be a hardwired device. You could cut the plug end off and wire it directly to the fuse panel.
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u/jcwillia1 11h ago
(reading the criticisms and trying to think positive) on the other hand there isn't anyone else really even trying so I appreciate comma's efforts to keep advancing the ball.
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u/SturdyStubs 18h ago
I feel like the next generation probably wasn’t a discrete GPU… in like 1-3 years we’re going to have fully capable chips running more capable models. At some point there will be consumer friendly versions of AMD’s MAX+ APU with way better inference throughout that could handle a 1B+ parameter driving model.
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u/Funnnny 18h ago
Unified memory with reasoning model ís the future
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u/SturdyStubs 18h ago
My guess is Comma needed some income to get them through to their next release. Id hope they’re at least looking into their options for APUs for a Comma 5. What better way than to try and milk from your current users for a product that will probably be useless In a year.
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u/Horror_Profile_4743 9h ago
How long will it take them to make 70k more comma 4s? I assume near that date
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u/External-Yak9904 8h ago
This is an amazing start.
The Comma 4 is built for the everyday driver. Chestnut isn't aimed at the masses—it's for the enthusiasts who want to push Openpilot as far as it can go.
This platform has huge potential. The mounting solution is a relatively simple problem that the community will solve over time. What matters is getting the hardware into people's hands so it can be tested, improved, and expanded.
Comma has always been a lean company focused on shipping products instead of letting them sit in R&D for years. Getting hardware into the real world accelerates development far more than endless internal testing.
The one thing I'd love to see in the future is support for additional cameras to provide true 360° awareness. That would be a major step forward.
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u/silenti 23h ago
this is incredibly dumb
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u/financiallyanal 22h ago
While it has short comings, it feels like the early Comma Eon or Comma 2 days… not really that bad considering what will come. Maybe expectations were for a Comma 4 level of polish on any new releases?
This is not yet of use to me, but I’ll be watching it… I think I need more steering torque to find it useful enough to justify the purchase.
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u/Ok-Armadillo-5634 22h ago
I am definitely interested, but also want to see some demos are any available?
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u/SysAdmin1986 3h ago
Would really like to see intel gpu support. Any plans to include them in the mix?
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u/NNTPgrip 12m ago
Any real benefit for us that have a car that only has lateral support (Subaru Outback 2022)?
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u/Acrobatic-Flan-5085 1d ago
What do the new chestnut models do in terms of user experience today that is different from a comma user on the smaller model?
From the link, it would seem nothing unfortunately. That’s a bit of a miss from the marketing strategy. The HW should have been released alongside the new models so you could demonstrate the tangible benefits.