Honda: add Prelude 2026 (HONDA_PRELUDE_6G)

[feldsam]

The 6th gen Prelude (BF1) is built on the Civic e:HEV platform and uses the same radarless Bosch messaging as HONDA_CIVIC_2022. Verified by comparing a captured CAN fingerprint from a EU-market car against honda_bosch_radarless_generated: every control and state message matches at identical lengths (0xE4 STEERING_CONTROL, 0x33D LKAS_HUD, 0x1C8 ACC_CONTROL, 0x30C ACC_HUD, 0x18F STEER_STATUS, 0x1D0 WHEEL_SPEEDS, 0x326 SCM_FEEDBACK). 0x184 present sets HYBRID; 0x1A3 present with 0x191 absent gives the eCVT automatic transmission type.

Specs are the Prelude's own rather than the Civic's: 2.605 m wheelbase, 1480 kg kerb weight, and centerToFrontRatio 0.37 from Honda's published 63/37 front/rear weight distribution. steerRatio is 13.65, taken from liveParameters after a real drive rather than from the spec sheet, which lists 11.3 end-to-end off-center. Lateral tuning is shared with HONDA_CIVIC_2022.

FW versions are captured from a EU-market car. All six ECUs carry the 36W model code, distinct from every other Honda in the database, and match_fw_to_car resolves the capture to exactly one candidate including the degraded cases: eps and vsa are non-essential on radarless Bosch cars and are lost without comma power, and the match still resolves uniquely with only fwdRadar and gateway.

Demo

Short clip of openpilot steering on the CI test route (49d0fc1df3e7320b/00000002--d2df953add).

Validation

• Dongle ID: 49d0fc1df3e7320b
• Route: 00000002--d2df953add

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[github-actions]

Car behavior report

Replays driving segments through this PR and compares the behavior to master.
Please review any changes carefully to ensure they are expected.

Testing 154 segments for: HONDA_ACCORD, HONDA_CIVIC_BOSCH, HONDA_CIVIC_2022, HONDA_CRV_5G, HONDA_CRV_HYBRID, HONDA_HRV_3G, HONDA_INSIGHT, HONDA_E, HONDA_PILOT_4G, HONDA_CRV, HONDA_FIT, HONDA_FREED, HONDA_HRV, HONDA_ODYSSEY, HONDA_PILOT, HONDA_RIDGELINE, HONDA_CIVIC

✅ 0 changed, 154 passed, 0 errors

[mvl-boston]

Awesome that you got a Prelude tested. Couple things that should help comma review:

• You don't need to modify cars.md. The values.py update will autoadd to cars.md.
• In connect.comma.ai, can you do files -> upload "all logs". That gives more canbus granularity which they usually want to see on a new car log.

[feldsam]

Hi @mvl-boston, I did excatly you wrote, I hit upload all logs button. You dont see what you excepted? Is it a issue? This is based on Civic Hybrid model, so no special changes for Prleude.

[mvl-boston]

Hi @mvl-boston, I did excatly you wrote, I hit upload all logs button. You dont see what you excepted? Is it a issue? This is based on Civic Hybrid model, so no special changes for Prleude.

I see it now. Will add it to all my forks, but you'll have to wait for comma to review and add it for official support.