I was looking at the GM Tech 2 at some point since all my vehicles have been GM and I would get many years of use out of it for diagnosing issues and potentially re-programming their ECU. Well GM has upgraded and the new diagnostic tool is called MDI and it requires an annual subscription to work. This is the: GM Tech 2 Deluxe with 2010 Software and Candi Module This sells for about $4500 brand new and is the old technology. This is the: GM MDI Multiple Diagnostic Interface for Tech 2 The hardware sells for about $1500 brand new and replaces the Tech 2. It looks a little strange right? Well it is the interface to connect your OBDII to your laptop with Tech 2 software installed on the laptop. It has a connection for the OBDII to the MDI and leaving the MDI you have the option of a USB cable or a Cat 5 network cable (Much higher bandwidth than USB). That "should" relate to faster data logging and true real time displays in gauges and charts on your laptop. GM lets 2 different manufactures create these diagnostic and programming tools: Bosch Diagnostics: http://www.boschdiagnostics.com/TESTEQUIPMENT/DIAGNOSTICS/SCANTOOLS/MDI/PAGES/MDI.ASPX OTC: [*=1]http://www.otctools.com/products/gm_mdi It also requires an annual subscription from AC Delco found here: [*=1]https://www.acdelcotds.com/acdelco/action/subscribehome So the cheapest you will get away with one is for the $1500 + the annual $1395 fee for the Tech 2 and Service Programming Package (if you want diagnostics and programming features to be enabled). I called ACDelco and asked them if these subscriptions were only for dealers large chain auto shops and they said that anyone that wanted to would be able to purchase either the Tech 2 or the MDI and a subscription to the service (Why woudn't they right). Anyway I am posting this for information purposes if anyone is interested, I am, but not with the annual subscription fee. I guess its not for me then.