Who this is for
GM owners whose Chevrolet, Buick, GMC or Cadillac is missing from comma's list.
comma fourcomma 3X
OPGMInstall softwareSome effort
OPGM: openpilot for unsupported GM cars
Install opgm/release as Custom Software; it adds pedal and cruise speed modes and steering-only support for some GM cars.
You need
- A comma four or 3X with the GM harness
- Your car's exact model and year
- Optionally a comma pedal for speed control on older cars
In plain words
Why this guide matters
Many Chevrolet, Buick, GMC and Cadillac models have lane keeping but are missing from comma's list. OPGM keeps stock openpilot behaviour and adds those GM cars, including some that get steering only. You install it by typing opgm/release as Custom Software on a comma four or 3X.
The short version
What the full guide walks you through
Check the OPGM car list for your model.
Reset the device and choose Custom Software.
Enter opgm/release, or opgm/nightly for the latest.
Pick the speed control mode that matches your hardware.
Before you start
- Steering-only cars will not brake or accelerate for you.
- Community fork; comma will not support issues on it.
The full project page belongs to OPGM. Checked on September 10, 2026. Their last update was June 27, 2026.
Quick answers
Questions people ask
Is OPGM different from normal openpilot?
Barely; it changes GM code only and leaves everything else stock. Its stated goal is stock openpilot for unsupported GM cars.
Does my Bolt need a pedal?
For EVs without adaptive cruise, OPGM strongly recommends a pedal interceptor for speed control. With it, the Bolt gets full regen braking.
Where is the car list?
In the CARS.md file linked from the OPGM project page. Ask in the OPGM channel on the community Discord if unsure.
Check your car
Cars this guide talks about
Support changes by year and trim. Open your exact car before you buy anything.
Related
More guides like this
All community guidesNot sure this is your path?
Check your exact car first, then choose software and hardware.
Photos: comma.ai. Guide content belongs to OPGM. CommaGuide is an independent guide and is not affiliated with comma.ai or OPGM.
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