Vekke -
The basic version of DriveGain is free, but I also think it does NOT talk to the OBD II port. I think it uses GPS to determine your driving style. I assume that your solution would require a (wireless?) OBD II interface. Here are OBDII->wifi options :
Innovate Motorsports OT-2 - Transform your iPhone or iPod into a wireless gauge, data logger, dyno, efficiency meter and OBDII scan tool.
OBDii IPhone obd2 - scanner wifi Smartphone: iPad iPod
The cheap ones seem to be (low power?) bluetooth :
ELM327 V2 BT Wireless OBD II Reader
CarloSW2