I'm sure that CARB has it in their sights to require historical data in the future. And so as CARB goes, so does the nation. Auto manufacturers spend enough money on their controllers, that they don't want to engineer two systems. Plus, it would mean that a car bought in Oregon couldn't later be resold in California as a used car (well, it just couldn't be registered there).
What a bunch of socialists!
Controllers have keep alive memory that retain memory as long as the battery is connected. They use this to map engine/sensor characteristics for better emissions and performance. Fault code data is also stored there. A fault would have to occur x number of key-on cycles before being stored as a code and would have to be absent for x number of key cycles before being removed.
While a controller has a timer, it start up from zero on every time you turn the ignition key on. It cannot remember calendar time if it wanted. There are no plans to incorporate calander time in any controller at least up to 2006.
I have incorporated histogram data for racing applications that could be downloaded showing times spent in certian RPM bands. The drivers always swore they never used the engine to brake nor even overrev the engine. (Data shwed otherwise