I have a few questions, maybe you will know the answers:
Can I connect a car on-board computer to inductive speed sensor?
And what would be different if I connect a hall sensor instead of inductive sensor?
Thanks in advance
The speedometers I've heard about are driven by a cable attached to a wheel. Some cables terminate with a spinning magnet, which drives (by induction, or similar concept) a disc attached to the speedometer needle.
If you can get close to this spinning magnet then you can put a sensor close to it.
Come to think of it, some onboard computers are already connected to the speedometer sensor, one way or another.