My buddy has the 3rd gen that is silver with burgandy leather, I know that they are rare but I dont know the model. He has no mods. It seems that the coolant just dissapears and then the coolant buzzer goes off. It never over heats and there is never white smoke when he's driving or when he starts it up,so I don't think that it's coolant seals. The problem is that we can't see water dripping anywhere, and there is no coolant in the cabin from a bad heater core. It does however overflow after he turns it off, but the temp never gets high. I'm a TII pilot, so I can't see **** under the hood of a 3rd gen that even looks like a rotary engine so I have'nt been much help. If you gentlemen and scholars have any ideas, your feedback would be much appreciated. Thanks in advance, Mike

 

It sounds like bad o rings. I don't have time for a long response, but search for champagne bubble test, or o ring test. This overflowing I assume is from the coolant overflow bottle, this is one of the symtoms of bad o rings.

 

Turbo coolant hoses are my bet.

 

If one of the lines going to/from the AST is pinched it won't separate the air from the coolant during heatup/cooloff cycles. Air will build up in the system over time and it will push all your coolant to the overflow tank (ask me how I know).
A bad coolant line to the turbo is certainly a possibility as well.