I also recommend purchasing this 20 pin adapter if you have an older vehicle with the round port under the hood. VAG com USB Cable OBD II 2 FTDI KKL 409 1 VW Audi VCDS KTM Triumph Tuneecu BMW | eBay You need to purchase this cable which will work on models up 2007.

Windows 8 & 8.1 will work too, but there have been reported problems. If you wish to do so, I can not be held liable:) You can seriously damage your car using some of these programs. I'm no expert, but I will do my best to help all that are willing. I was lucky enough to stumble across this information and feel every BMW enthusiast should have access to it too.