just some random thoughts:

 first, I admit I am no expert.

 there are 35-40 mpg cars available right now - but not enough people
buy them........I have plenty of friends and family still buying
Navigator Ls and the like and they don't give a rats behind what the gas
costs.  they don't care that by using twice as much gas as necessary
they are shortening supplies and raising prices for others.  I live near
the Great Lakes:  the average Joes have cut back on their boating in
putt-putts.......the guyz with the 50 footers could care less - Filler
Up !!!!

 still can't figure out where all that clean, green electricity is
going to come from when I plug my car in for its overnight
charge.....somewhere else I guess (as long as it isn't in Teddy
Kennedy's back yard).

 and a hundred years from now the new "Love Canal" will be where all
the old battery packs were dumped.  how much does a battery replacement
cost for some of those cars, anyway.

 I'm an old fart:  my first care was a 10 year old '56 Packard 400 (!)
it weighed 5000 pounds, had a 305 hp, 374 V8, was faster than stink,
huge, comfortable, safe.....and got no less than 15 mpg no matter how I
drove it.  My LHS gets 24-26 on the highway....and 13.5 in
town.......about 3600 pounds, underpowered and slow.......progress?

 it'll never happen, but the only solution is a form of rationing:
everybuddy is entitled to X number of gallons at a decent
price.........you can use it frugally or drive a guzzler and only go
half as far......once you've used your allowance, you can buy more - and
pay thru the nose for it.  ir maybe a total energy allowance:  let
Barbra Steisand lecture us on saving energy in one of her mansions -
with the heat shut off.

,  btw:  ethanol..... my town of 50,000 was glad to hear that we were
going to get an ethanol plant  (although  worries about the price of
corn/soy, cost to feed livestock, cost of dairy, meat etc are concerns).
anyway, the City Fathers in their wisdom sold the company a bunch of
land at about 5% of market value and granted tax abatements and the
usual inducements to build the plant.  then someone took the trouble to
crunch the numbers on the proposal and learned that we don't have enough
electricity, natural gas or water to run the damn thing and the ethanol
it would make would be prohibitely expensive anyway and provide only a
fraction of the energy it would take to make it.........then the
"ethanol" company admitted they didn't have the money to build the plant
anyway.  but now they've got 100 acres of prime land.

........like the old Saturday Night shtick:  "because you'll believe
anything"

I'm not sure.  I think it might be more of an amperage thing than
voltage.  If it is voltage then transformers could provide the step up.
 However, they could probably have it so the gas engine runs long
enough to charge the batteries if they are low.  Have the engine
automatically kick on and recharge the batteries while the wife is
shopping for three hours.  When she's done shopping the batteries will
be topped off.   This could be something the driver could toggle on and
off.  Or like I said earlier, have a small 2-3 cylinder gas engine tied
to a generator to supply electricity in a pinch.  The nice thing about
this is the engine would only have to operate within a small rpm range
and this would let it be designed and tuned to run most efficiently like
the current Honda type generators.

Another trick thing to add would be something like a Peltier cooler that
would use the temperature differential between the exhaust gas and the
ambient air to generate electricity from the waste heat from combustion.
 I wonder how much current could be produced this way.  It would help
to increase the overall efficiency when burning gasoline.

Damn, I wish I worked for a car company!  I could keep myself highly
entertained.