Here's an example of what you can get for a compact car:
http://cgi.ebay.ca/ws/eBayISAPI.dll?...ht_1038wt_1186
I would pick a front wheel drive, 5 speed with a blown engine. Those usually go for under $500. You can expect to spend around $5000 for the motor, speed controller with regenerative capacity, wiring, batteries and charger. Lithium cells currently cost about $1.25 per A/hr.
I have a 6600ma/hr RC Li-Po battery weighing 430g. It can deliver 6.6A for one full hour and weighs less than a pound just to give you an idea of what battery technology is at. I have also found that Li-Po batteries stay cool thruout it's charge and discharge cycle.
I would be interested in taking a look at your Neighbor's S10 on our next visit John