Paul:
There is actually one more now, our Chinese friends call it a MB Star C4, I have a older C3 and a C4 and upgraded my laptop from a Dell to a Panasonic toughbook.
First I have to say this is a unbelievable cool tool and it will pay for itself no matter how much you spend on it.
The software can be installed on almost any laptop, but if you use a compact or C3 you need a serial port.
MB Star C3 is the older version I have seen some roomers that you cant use it on vehicles newer the 01-2014, I have not been able to verify this. (have to wait 10 years to afford a 2015)
use serial port for communication
no WiFi or Ethernet
MB Star C4 is the latest you can get on the aftermarket and is still used in most MB service centers at least in my area
uses WiFi or Ethernet for communication and is faster
has a LCD display and 2 status LED’s
you can install a 6 AA rechargeable’s to keep the unit from rebooting on disconnect.
I like the WiFi option I can sit in my heated living room and work on the Benz in the Garage.