[ecomodded]

I like the idea of a large battery bank for a alt. delete, but It would have to be done more efficiently than todayican's example.
Here is a list of changes that can be made to reduce your amperage consumption-
Replace heater fan with 2 low watt 12v fan's in tandem that draw minimal amps perhaps 1 amp each.

replace absolutely all of the interior bulbs with LED's.
Replace all of the exterior bulbs with led.
Find lower watt bulbs for your head lights, if you wanted you could mount some bolt on led pods.

Replace car stereo with mp3 player plugged into low watt powered speakers.

Use a few solar panels to on dash and back parcel shelf to charge a auxiliary battery that powers your speakers, fans
and interior lighting.
Now the car may run on 15 to 20 amps most of the time and no more than 30 35 amps at any giving time but more than likely the car will be using 20 amps for most of its driving. A person could use a smaller /cheaper battery pack to replace the alternator, making it more justifiable to consider implementing.
You would need a solar charge station at home to top up the batteries.