dp cars
http://www.dpcars.net used a back bone and is working on a composite chassis as well
as for batteries my time on solar car has tought me alot you must have a battery protection system with LI or Nickel batteries or you will kill them quickly. Also there must be a balancing system or you will see a big decrease in capacity or a fire neither of which is fun.
Li batteries can be purchased from
http://www.batteryspace.com if you call you can get a price discount.
We used the LG chem A size batteries and made our own modules and packs
Also if you can deal directly with Kokam you can also get a discount ( find some one who is Korean)
we used these a few years ago they have a zinc tab that must be welded not solder
batteries are still pretty expensive Ive helped built numerous $10k battery packs. The 1000 cycles will most likely never be reached there are always problems under volt over volt temp that will destroy them quickly
if areo is important to you read the book "The Leading Edge" its mostly solar car focused but full of good information