John,
I thought it was probably warranty related, I'm pretty sure these battery packs aren't going to make it 10 yrs/150K (CA) and I have my doubts about the tranny too, not to mention the ICE starter motor/interface..
About maximizing mpg's, does anybody else drive like GaryG http://www.cleanmpg.com/forums/showthread.php?t=350 and is it damaging or putting undue wear to drive like that, very enlightening stuff in that article...