I was really skeptical at first and was looking at Carly but went ahead with the Topdon Topscan. I was really impressed with it and purchased mine at a good price from the UK via Car Dynamics (cardynamics.co.uk). I've had it for a week now and its helped diagnose a number of issues with my car to help resolve some rough idea I've had for months. Only negative is the 1 year subscription which I'll have to renew out of my own pocket.