stuff i learned from reading the document found at the link above:
twice as many vehicles are likely to fail an OBDII test compared to the tailpipe test.
the new test will also prevent or drastically reduce "clean scanning" a.k.a. getting info from a surrogate vehicle.
newer vehicles contain lots of information:
(Cal ID): a number assigned to a particular vehicle model to indicate the software calibration of the vehicle.
Calibration Verification Number
(CVN): This value is computed based on contents of the on-boards computer's software. Unique to a specific Cal ID, even down to identifying models or trim levels.
Vehicle Identification Number
: (VIN) we all know this one. some cars have it on their computer.