Originally Posted by Porschefile
Wasn't aware of Trackmaster, thanks for the info. Would you mind sharing a link to the external GPS and OBD I would need?
You probably won't need an external GPS, especially if you have a newer Android phone. I would try without one.
OBD -- check Amazon for "ELM 327" bluetooth units. You should be able to get one for <$20. If I remember correctly, you want one that is version 1.4 or newer, but you might want to double-check that (been awhile since I bought one). I would buy from Amazon and worst case, if it doesn't work, return it. Though I had no problems with mine and I just picked a random one from Amazon