Here's an old post of mine to help those who are interested in making a moderately longer (yet era length accurate) game. Yes I understand the game clock date is 'meaningless' but it really doesn't take that much work to get it to match up pretty well even for a 2000 turn game, so why not.

I'm mainly looking to get back into Civ when BTS is released, so if this method is no longer functional with Warlords, sorry.
Hey guys, I'm not sure if this has been brought up in another thread I'm not aware of, but there is a reasonably simple, if ugly, way of leaving the calendar set to years and still obtaining partial years per turn.
All you need to do is have a have a -long- set of gameturninfo's like:
<GameTurnInfo>
<iYearIncrement>0</iYearIncrement>
<iTurnsPerIncrement>1</iTurnsPerIncrement>
</GameTurnInfo>
<GameTurnInfo>
<iYearIncrement>1</iYearIncrement>
<iTurnsPerIncrement>1</iTurnsPerIncrement>
</GameTurnInfo>
(Which gives you .5 years per turn)
And, of course, you can get other fractions (on average) like .4 with
patterns like: 0100101001
Using this method I've got a speed running at 5 times the length of a "normal" game using an exact match in era length. Civ has no difficulty coping with having turns back to back that are the same year that I've run into. It's possible some of the autosaves might write over each other, but meh. Hope this was useful.