If you have an Android based phone for the Torque Pro program ($5).. this is what you would need.. No wires and you can just leave it hooked up and also see your cars performance etc.

http://www.ebay.com/itm/New-V1-5-ELM327-OBDII-OBD2-Bluetooth-Car-Diagnostic-Interface-Scanner-w-Software/330918035633?pt=Motors_Automotive_Tools&hash=item4d0c4080b1