YOUR OLD CAR CAN GET LANE CENTERING AND ADAPTIVE CRUISE FROM A 999-DOLLAR OPEN-SOURCE BOX
A camera box on your windshield and one cable plug gives your old Honda or Toyota adaptive cruise control, lane centering, and automatic braking with traffic.
by comma.ai
AutomationAI
- difficulty
- ●●●○○
- time
- an afternoon
- license
- MIT
- repo
- repo ACTIVE63,802 stars
●●●○○ · an afternoon · MIT · 63,802 stars · repo ACTIVE
WHAT YOU’LL NEED
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COMPAREE VERDICT
openpilot is one of the most established open-source driver assistance systems, with around 63,800 GitHub stars and a decade of real-world data behind it. It adds adaptive cruise control, lane centering, and automatic braking to cars that shipped with basic driver assistance — including used Toyotas, Hondas, Hyundais, and over 300 models in total. The catch: you must buy the comma four device from comma.ai (successor to the comma 3X) for 999 dollars including the harness for your car (prices have changed in the past), and your specific car must be on the supported list. Not all cars get the same level of support — on some openpilot controls steering and speed, on others only steering while the stock cruise control keeps the speed. The installation is reversible and comma's own setup guide puts it at about 15 minutes, but the first week of learning to trust the system will feel longer than the install. The single biggest risk is overconfidence — openpilot is not self-driving, and you must keep your eyes on the road and be ready to take over at any moment. For someone with a compatible car who drives highway miles regularly, this is transformative. For someone whose car is not on the list, it is a weekend spent researching alternatives.
IN THE REPO
GOOD TO KNOW
- —MIT license — unrestricted use, commercial or personal.
- —The repository contains the openpilot software stack; the comma four hardware (successor to the comma 3X) must be purchased from comma.ai.
- —Over 300 car models supported, but support quality varies — some cars get full longitudinal control, others only steering.
- —The car compatibility list lives in docs/CARS.md in the openpilot repository and changes with each release.
- —Installation requires a one-time harness plug behind the rearview mirror; no permanent modification to the car.
- —You are legally and physically responsible for the car at all times — openpilot is classified as a driver assistance system, not autonomous driving.
Parts to buy
2 itemsFrom our check of the build. Exact quantities and part numbers are in the creator’s BOM.
Can I build this?
Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.
Videos
A drive to Taco Bell
comma's own drive video; for installation, follow the official comma four Setup Guide video at comma.ai/setup.
More builds like this
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Start here
Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.
- 1.Check if your car is supported (The compatibility list is docs/CARS.md in the openpilot repository (also on comma.ai's compatibility page). Some cars are fully supported, others only partially. If your car is not listed, stop here.)
- 2.Order the comma four and correct harness (Available from comma.ai. The harness is model-specific; select your exact car when ordering.)
- 3.Follow the installation guide for your car (comma's official setup guide gives per-car installation notes and a video. Expect to pop off the rearview mirror trim and plug the harness into the camera connector.)
- 4.Complete the calibration drive(After install, openpilot requires a calibration drive on a straight road to align the camera. This takes 10-20 minutes.)
- 5.Spend a week learning the system's limits(Do not trust it immediately. Learn where it excels (highway lanes, steady traffic) and where it struggles (unmarked roads, complex intersections, heavy rain).)
Resources
Documentation, files and community threads for this build — we link straight to the original sources and never rehost the creator’s files.
KNOWN ISSUES
- Buying the hardware before confirming your car is supported — the compatibility list is strict, and partial support means you might only get steering or only get cruise control, not both.
- Assuming openpilot is self-driving — it is not, and treating it that way will put you in danger. You must stay attentive.
- Installing on a car with factory ADAS already enabled — some cars require you to disable or override factory systems, which may void warranties or trigger service warnings.
- Skipping the calibration drive or rushing it — a poorly calibrated system will ping-pong in the lane or disengage constantly.
- Not reading the model-specific notes — some cars have known quirks (e.g., Hyundai/Kia models may require a specific firmware version, Honda Sensing cars may need additional configuration).
- Overconfidence after the first successful drive — the system will eventually encounter a situation it cannot handle. You must be ready to take over immediately.
Is this legal?
In most jurisdictions, yes — openpilot is classified as a driver assistance system, and the driver remains fully responsible. However, some regions (notably the EU and parts of California) have restrictions on aftermarket ADAS. Check local laws before installing.
Does this void my car's warranty?
Possibly. The installation is reversible and leaves no permanent marks, but some dealers may refuse warranty claims if they discover aftermarket modifications. comma.ai does not provide warranty coverage for your car.
Can I use openpilot on a car without factory cruise control?
Usually no. Openpilot requires the car to have at least basic cruise control hardware (throttle-by-wire, electronic brake assist) to function. Check the compatibility list for your exact model.
What happens if I take my hands off the wheel?
The comma four has a driver-monitoring camera. If it sees you looking away or not paying attention for more than a few seconds, it warns you with escalating alerts and then disengages, and repeated violations can lock you out temporarily. Keep your hands ready and your eyes on the road.
Can I run openpilot without buying the comma four?
Technically yes — comma itself documents running openpilot on other hardware, but it is not plug-and-play. Practically, the comma four is engineered for automotive environments (temperature, vibration, power stability) and DIY setups are fragile and potentially unsafe.
Community builds
No community builds yet — be the first, we feature the best ones.
Discussion1
FROM THE COMPAREE TEAM
Over 300 car models are supported, but the experience varies — on some openpilot controls steering and speed, on others it steers while the stock cruise control handles speed. If you have tried openpilot, which car did you install it on, and did it meet your expectations?
comma.ai
Founded by George Hotz in 2015 after he built a working self-driving system in his garage, comma.ai has spent a decade refining openpilot with data from thousands of users driving millions of miles. The company sells the hardware and an optional comma prime subscription, and maintains the software as an open-source project.
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DISCLAIMER
- Comparee is not the author of the projects featured here. All rights to each project belong to its creator — every page links to the original source, and we never host creators’ files.
- Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
- Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
CompareeTEAM2mo agoedited
Practical notes from our verification: openpilot has around 63,800 GitHub stars and the software is MIT licensed, but for a plug-and-play install you need comma's own hardware — the README names the comma four, which comma sells for about 999 dollars with the harness for your car. Running openpilot on other hardware is officially documented, though not plug-and-play. The repository is very actively maintained, with commits landing daily. The supported car list (docs/CARS.md, 335 entries) is extensive but nuanced: on some cars openpilot handles both steering and speed, on others it steers while the stock cruise control keeps the speed, and many have minimum speeds below which steering or acceleration is not available. comma.ai/setup has a short official installation guide with a setup video, and the official Discord is the place for car-specific questions. The biggest surprise is not the technology but the responsibility: this is a driver assistance system, and you stay in control of the car at all times. The afternoon you spend installing it is trivial compared to the time you will spend learning to trust it appropriately. Correction (4 October 2026): we re-checked this page line by line against the project's own repository, documentation and videos, and fixed errors in earlier versions.