Thanks for the kudos... I'm going to need a new hat
I think I'm siding with the above suggestions - sidecars suck. Never even driven a motorcycle and I still think they suck. Esthetically, they are ugly. Practically, they seem like they would be a pain to maneuver compared to a bike with a trailer, or a car. Geekilly - they increase your frontal area for wind drag.
I didn't know that the Volt did not charge the batteries. That's interesting. I suppose if that were your design criteria, then you just need to price out a generator that can provide enough amps to accelerate your car on a hill at your system voltage.
I work on one device that is both 120AC and 24VDC powered (the battery is backup in case of power failure, the board actually runs at 12V after a power regulator. When the device is plugged in, the AC side of things provides about 3 volts higher than the battery. This way, the battery recieves a "constant voltage" charge, which may not be greatest, depending on your batteries.
I rather doubt that your battery charger could do anything useful... it takes 6 hours to charge what it takes 20 minutes to use. Otherwise, that'd be a great idea.
Interesting project you've got going here... making it compatible with both the bike and car is certainly tricky...