[haha]

...What does the CAN refer to? Is there any point in getting a higher model number, e.g. the 3140?...

CAN data transfer protocol commonly found in cars.

http://en.wikipedia.org/wiki/Controller_Area_Network

ODBII (On Board Diagnostic) is yet another data transfer protocol (ODB is the first gen)...anyhow, it's a standard required by the US EPA...not car specific. Not to mention model specific. Though, some auto manufactures don't conform to SAE standards...