oops i didnt see that there was other battery posts... lol
oh well... Any extra information postings would be nice though. How many MPG do you think the honda insight gets without a IMA battery on a manual tranny?
Hyper MPG (highway) will be almost identical. The city drive cycle may suffer 10% +- w/o auto stop.
The biggest "problem" isn't MPG. Since the IMA and alternator functions are integral the IMA battery will eventually require replacement to allow proper 12v operation. They 2 systems are interdependent and there have been credible reports in here that confirm the above.
Adding a conventional 12v chargins system won't be easy and even more so if your AC equipped (no location for alternator mounting).