Anyone interested in developing an OBD Arduino based fuel economy gauge should post here. So far, I have been working on one based around an ELM323 OBD to RS232 adapter. Some previous discussion on this was on the other thread (
Any interest in developing an open source fuel economy gauge/computer?)
Currently, I was able to connect to the ELM and send it commands. However, when sending OBD commands (010c), the response is "ELM INIT:...>" without ERROR or OK and no real data is received.