I'm using the ELM327, works great so far my car is a 2003 UK 350z. This is the exact one I bought
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=140527841238&ssPageName=STRK:MEWNX:IT
Heres mine running, hopefully installing a smililar android tablet in my car soon
Could do with changing the colour of the numbers to match the car