One type of battery frequently considered for automotive applications is the Nickel-Zinc battery. It contains no heavy metals to contaminate landfills, stands up well to many charge-discharge cycles, and is available at reasonable cost. Nickel-zinc batteries offer considerable weight and volume savings over lead-acid and nickel cadmium batteries of similar capacity. Typical batteries offered by Evercel reach Specific Energies of 60 Wh/Kg and Energy Density of 110 Wh/liter.
The Nickel-Zinc batteries are often found in lawnmowers, scooters, and electric wheelchairs, as well as marine applications, such as trolling motors.
In several instances, builders have been inspired to modify standard gasoline powered automobiles. You can read one such story of a successful conversion at http://pw1.netcom.com/~fw/id1.html
Other automotive battery applications:
Lithium-Metal-Polymer batteries for electric vehicles
Zinc-Air batteries for electric vehicles