I've been using Torque[1] for about three years now. It's got a pretty nice UI to show just about anything your car outputs via OBD-II, and lots of things that

I've been using Torque[1] for about three years now. It's got a pretty nice UI to show just about anything your car outputs via OBD-II, and lots of things that can be derived from that, as well as integrating GPS and accelerometer data. You can log the data to your phone, as well has have it uploaded to the cloud. The only time I've really used that data was the time some jerk stopped me, cursing at me for driving like a maniac and endangering his children (who he'd been allowing to play in the street). With the logged data, I was able to show that from the time I turned onto his street, I had been going no faster than 10mph below the limit. The OBD-II error-reading software is very useful. It showed me that the Hyundai mechanics were completely incompetent. After holding my car in the shop for a week, they finally concluded that the problem is exactly what these diagnostics told me they were (plus 10 minutes of googling). [1] https://play.google.com/store/apps/details?id=org.prowl.torque https://play.google.com/store/apps/details?id=org.prowl.torq...