I personally

setup a new Google account with minimal personal data, just for the sake of authenticating with the phone. I don't use that account for anything else, so there's no additional data connected to it. You can choose not to synchronize contacts, emails, etc with Google. You can turn your GPS off when not in use. If you use a GPS program, like Google Maps, it's given that it needs your location for that purpose (but I think even that can be declined). You can terminate the app when you don't use it and then turn off your GPS when you don't need it.

As a side note, I looked up the permissions GasBuddy requires:

- Full Internet access: Allows an application to create network sockets.
- Prevent phone from sleeping: Allows an application to prevent phone from going to sleep.
- Read phone status and ID: Allows the application to access the phone features of the device. An application with this permission can determine the phone number and serial number of this phone, whether a call is active, the number that call is connected to and the like.
- Your location: Coarse (network-based) location and fine (GPS) location

Privacy should be a concern with apps, too.