With the Plug-In FEH that Ford and others have been testing, I see that a conversion from our non plug-in models may be possible at a reasonable cost in the future. Since I ordered the '09 FEH, I have changed my opinion about selling my '05 FEH. The fact that Ford is taking our eCVT to 120 MPG in the Plug-In FEH prototypes raises questions that future technology will lower the cost or make our FEH/MMH a good investment to convert to a Plug-In battery system in the near future.
What if all of a sudden we find the cost of fuel drives up the market on Hybrids to the point that our old FEH/MMH are worth much more by buying them and converting them to 120mpg plus hybrids! All of a sudden we have a vehicle that does not depreciate, but appreciates instead.
Now that I see the 40mph EV limit for the present Ford eCVT, I also see that battery assist to the engine can increase mileage to over 90mpg. I found this out during a highway trip at 60mph when my battery was doing a reconditioning to ~82% and then discharged using the electric motors at that speed.
Folks, good luck with your investment!