Jed,
Frankly, I see no point to going that fast without the ICE. The
ICE is more efficient than the electric motor at that speed.
Actually no, it is far less expensive - perhaps half the cost - to
go with a larger electric motor and batteries recharged at
night-time grid rates 6-7 cents per kwh than to use gasoline at
$3.00+ gallon - which works out to 18 cents per kilowatt hour
equivalent for a vehicle getting 45 miles per gallon. For
cross-comparison, you must deduct the inefficiency of the
batteries 70% (some are better) and the electric motor 90% (some
are better) but all-and-all it is half the cost to use off-peak
grid power than gasoline.
Matter of fact - didn't you supply those figures earlier? I
believe this is the site:
http://pdftohtml.logicx.net/pdf2html.php?url=http://avt.inel.gov/pdf/fsev/costs.pdf
Jones