For Information only, and i appreciate this is not going to be as good as tech-2 or the like, however it works for the novice
A few weeks ago, i was asking about an Android App called torque, and the use of the bluetooth dongle for the car to read/clear ecu codes.
Well i took the plunge and bought it all
Ebay: Bluetooth ELM327 OBDII reader
Android Market: Torque app £3
Here's what the app interface looks like
Other random screen
The data hasnt been populated yet because i haven't been out in the car, however it uses engine displacement and weight to gather rough data about BHP and stuff like that. I dare say it wont be very accurate.
I plugged the bluetooth dongle into my car, paired it with my HTC Desire, opened the app and it started displaying info. I was able to read codes (there was none) and if so clear them too. It was handy for me because i thought my engine coolant sensor was knackered, however the readings i got from this helped, as i could create a custom dial to monitor it.
It only seems to work with an OBDII ELM327 dongle, and i bought this one from ebay (Item number: 220678938329) It took about a week and a half to come, however its that you need.