Life on Mars TV show - Need an answer

[NQAS]

I just finished watching the British tv show, Life on Mars (with John Simm).

I would have put money on the likelihood that Tyler was in a coma and that 1973 was a coma dream (if there is such a thing). How else would he have known about the different Miranda warning (British version thereof)? And computers and nanotechnology and better policing and forensics, etc.?

And yet. . . at the end of the series, I still don't know what year is real and what is the dream?

I think that the follow-up series, Ashes to Ashes, which I haven't watched yet, suggests/implies that 1973 is real. But without that show, what was I supposed to think about the end of Life on Mars?

Some other random thoughts. The DCI that showed up in the last two episodes was named Frank Morgan. Tyler saw him as his surgeon. Frank Morgan is the name of the actor who played The Wizard of Oz. So what? Or key clue?

Gene Hunt. So maybe it was a "hunt for genes" that was critical in saving Sam?

A point in favor of 1973 was his coma dream belief that Maya left him while he was in a coma. Who does something like that?

So, convince me. And I'm gonna start in on Ashes to Ashes shortly.