You get a bluetooth device that plugs into the odb port, or a patch cord that you connect to your raspberry pi. There are fancier ones with more features, that can do more than just report signals like watch for certain signals or changes.
Qwen 4B and 9B should be faster and better reasoning than Gemma 4 E4B. Other good options for that much RAM are Gemma 4 12b and 31b. Gemma 4 E4B would be better for native audio, but OP is using Whisper for STT so prob doesn't matter
What's the hardware situation to get OBD data?
You get a bluetooth device that plugs into the odb port, or a patch cord that you connect to your raspberry pi. There are fancier ones with more features, that can do more than just report signals like watch for certain signals or changes.
https://www.amazon.com/s?k=obd+bluetooth+adapter
Cool — but is that model really the right choice for the task?
I guess it is only 3B active which helps a lot but is Gemma 4 E4B not more practical?
Qwen 4B and 9B should be faster and better reasoning than Gemma 4 E4B. Other good options for that much RAM are Gemma 4 12b and 31b. Gemma 4 E4B would be better for native audio, but OP is using Whisper for STT so prob doesn't matter