At this moment, the auto save saves the game every year. So, when the game is playing high speed, auto save has a high frequency, but when the game is paused, auto save will never save the game.
The is still not stable, so it crashes a lot. Auto saved games are handy to recover from a crash. But when I pause the game, to edit an complete city, and after 30 minutes the game crashes, I loose those 30 minutes and can retry again.
But suggestion is: Make a setting which defines how often a game is auto saved regardles of the game speed (for example: every 1, 2, 5 or 10 minutes). This will result in less frustration after each crash.